For several months now, I have intermittently heard a clunking/grinding noise when accelerating, usually at low speeds like when merging onto the interstate from service roads. And it only lasts about 1-2 seconds. The first few times it happened, I crawled under the truck to see if anything was dragging or loose and never see anything wrong. This morning it did it again after taking off from a red light. Probably going 15mph and maybe in 2nd gear. This time it threw a CEL and the codes read p0700 and P0735 and put it in limp mode. I cleared the codes and went on about my business. It made the noise once mor etoday without throwing the codes and seems like if I let off and accelerate slowly, it stops. After reading some threads, it seems that the t-case might be slipping out of gear. My plan is to drain the t-case and see if there are any shavings. I put in a used transmission last year and did the t-case pump rub kit at the same time and didnt see any evidence of problems when I had the case split. I have put about 60k miles on it since then. my truck has 210k miles on it now. No programmer on the truck and this has never happened during hard acceleration or towing. Any advice?