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49 Posts
Discussion Starter · #1 · (Edited)
Ok so I’ve been researching some Power steering products/upgrades, fixes and info so working on compiling it.

There may be wear in the steering wheel, or other components. So if there's steering wheel play one must find the worn/failing components. For starters there's a couple screws in the top of the steering wheel. It's shown in pretty good detail in this vid.

You might have some steering wheel play from poorly adjusted or worn worm gears. There’s vids of 1 adjustment of the bolt on the cover with the 4 bolts. That’s frequently adjusted but isn’t generally the correct adjustment and frequently causes more harm. The wheel free play is actually the preload of the input shaft. It’s described and illustrated in this vid

For rattling clunky sounds and wheel vibration when driving and going over bumps it may be the steering shafts. Usually it's the upper, but the lower can wear out too. Order online for best prices. There's also a steering Bearing that's all plastic. The older generations are Easier than the LMM, which requires cutting a steel shroud off the lower column and it doesn't pop out as easy. There's only 1 vid I found of the 08-13 generation showing it GM part No 15775851.

Primarily for LMM but much of it overlaps others. Just verify part #’s, most factory parts\pricing are from Rockauto, Gmpartsdirect etc. Local dealer will be much higher. Not all numbers list as compatible with models but users have found they fit.

Upgrades- LMM P/N listed

1. Swap to the 2011 Hydroboost for better operation AC Delco 178 1036

2. Add a P/S cooler 918-326 Dorman, GM 26078989 or replaced by 15295847 $107- Otherwise 25805706 $73ish is listed to work

3. Apparently the original Delco fluid operates better in these systems rather than even synthetic

4. Add a P/S fluid filter

5. Flush your P/S fluid(search for vids/info)

6. Upgrade to the 6 bolt Gearbox case as listed below

Hose info- LMM P/N listed

A. Power Steering Pressure Hose - GM (20930009) $55 Pump to Pass side of Hydroboost- OR Gates 358980 $13 steel bent-> to hose → to steel bent

B. GM return hose 15137987 $45 Gearbox to Pump-- steel line to hose and clamp on--On gearbox the outside line(smaller of 2 gearbox fittings) Or Gates 352924 $41

C. GM Pressure hose 15295841 or Gates 365453 Drivers side of Hydroboost to Gearbox Hi pressure, On gearbox the inside line and runs rearward along frame rail back to Firewall then up to Hydroboost (larger of 2 gearbox fittings)

D. Outlet hose 15804953 $57 Hydro low pressure return to Pump --Long flex hose Or Gates 363520 $30 Not usually needed but one can use regular 3/8" ID oil cooler hose also


The standard gearbox is a 4 bolt top and rumored to be undersized and inadequate for today’s weights, diesel engine, lifts and tire sizes etc. So the theory is they wear quickly. The upgrade is a larger case body which contains a larger shaft/gear and evidenced by the 6 bolt case. It closely resembles the upgraded box option for maybe a 14-16 Dodge Ram 2500, maybe a different output splines etc. There’s many rebuild brands but many of the part store don’t generally tend to last long and have questionable quality. So a few top rebuilders emerge. Redhead and BlueTop have decent products in most cases. Some claim Redhead has gone downhill recently.

BBB Industries is also a very well known power steering manufacturing supplier and appears to supply many of the top brands. So one of the best upgrades is getting the 6 bolt case. One of the complications is you may need/want to switch to the 4 flat 32 spline Pitman as most of the cases have that. If you need the 4 flat 32 spline Pitman it will be a K6536HD, which are usually cheaper than the 3 spline also. But there is a box with the 3 flat 33 spline. You can count the splines by getting under there and using a mirror to see back side and verify the number of splines. 3 is the most common factory option.

BBB Industries
Technical & Customer Support

Phone: 800.280.2737
Mon. - Fri. 7:00 - 7:00 CST

Technical specs for P/N
^ Then click on Part Search and input part number you want info on. Then product will popup, click on it and then Attributes for specs
If link doesn't work should be able to search for their site, then click on ECatalog at top, then BBB catalog or other brands

BBB Industries sells the steering gear under Multiple names such as BBB, New Advantage, Genco, Vision-OE, Wilson
The "N" in the part number denotes NEW. So the straight P/N digits is the rebuilt, so Nxxx-xxxx means that P/N is NEW

The gearboxes normally have paint marking on them and engraving with a serial number for tracking, QC and identification. The NEW have a lifetime warranty

As of RIGHT NOW 8\4\2021 BBB Industries says they are sending the 6 bolt & the OEM 4 bolt as the N503-0178 with NO way to differentiate which it is without a physical box inspection. I've been in contact with their management team and technical support. Since they are advertising the 6 bolt upgraded case, but shipping the OEM replacement 4 bolt. I will post here when I have firm details. I tried 2 different suppliers with the same 4 bolt results.

As of 8/13/2021 their position is they are an OEM supplier and they build to OEM specs(the 4 bolt). As I understand it they use multiple suppliers and will use whatever case/parts they can get, in the end they will supply at least the 4 bolt case which is the Original OEM specs. The 6 bolt is essentially an upgrade in my opinion, they wouldn't confirm or deny that with any direct statements or specs etc. They provided me some pics side by side. In the end they were awesome to deal with and agreed the pics can and would likely cause some confusion. They were gonna have their teams do an audit so to speak to make sure the products match the units they ship out. As well as try to put a disclaimer of some sort on the pics.

I communicated with multiple high ranking employees in emails and 3 way calls. They were always very professional, prompt to reply, knowledgeable, understanding and tried to fully understand the whole issue and reach a common ground. In the end I was able to get a special 1 time deal on the 6 bolt, I'll post pics below for your information and evaluation.

In the end the 4 bolt is a NEW unit and will likely last you just fine, it's hardly any more than a rebuilt.

Pitman Arm
K6536HD 4 flat 32 spline
K6654HD 3 flat 33 spline (common)

6 Bolt Upgrade boxes (Physically verify 6 bolt cover) No way to select many pics are wrong

BBB or Aliases N503-0178 6 bolt $502 4 flat 32 spline

Bumper To Bumper BBB N503-0178 $544 4 flat 32 spline

Oreilly New Advantage N503-0178 $687 32 spline 4 flat 6 bolt 3.25 turns to lock

PSC SG039 6 bolt 4 flat 32 spline $695

Napa BBB- 391120N 6 bolt 4 flat 32 spline $924

Bumper to Bumper BBB N503-0153 6 bolt 3 flat 33 spline $520ish (not verified to fit/work yet)

Or Ebay

4 Bolt NEW OE Replacement

BBB or aliases N503-0188 $520ish 4 bolt 3 flat 33 spline
Bumper To Bumper BBB N503-0188 $520ish 4 bolt 3 flat 33 spline
Napa BBB – 391191N- $819 4 bolt 3 flat 33 spline

4 Bolt Reman

Bluetop Reman Gearbox 2873150 $450 3 flat 33 spline 4 bolt

RedHead Reman 2873 $406 3 flat 33 spline 4 bolt

BBB 503-0188 $190 3 flat 33 spline 4 bolt

Napa BBB – 391191 $389 3 flat 33 spline 4 bolt

Delco Reman 36G0166 $224 $225 core (Or 19321421) 3 flat 33 spline

9 Posts
Excellent write up, thank you for taking the time to throw in part numbers and prices. Been looking at replacing my gearbox and hydro boost for some time now.

49 Posts
Discussion Starter · #3 ·
Excellent write up, thank you for taking the time to throw in part numbers and prices. Been looking at replacing my gearbox and hydro boost for some time now.
You're welcome, took me a long time researching to find out exactly what some were talking about and the different brand names etc.

Premium Member
3,429 Posts
Pretty sure the LMM pump is being used on the GMY 800 trucks as an upgrade, as well.

49 Posts
Discussion Starter · #7 ·
This is the 6 bolt case on the left and 4 bolt case on the right. You can make your own determination, I know what my nonengineer opinion is
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