Reverse clunk noise??

[Kimper]

I have a 76 Chevy k10 with a th350, np203 and 12 bolt rear end. I brought to a shop to get the rear end looked at because with the rear wheels off the ground and the tranny in neural I couldn't move the rear tires forward. It would also clunk when put in reverse so I thought the backlash was out. Well the spider gears were messed up along with the ring and pinion so I had the whole thing rebuilt. The truck seemed fine when I got it back and everything was great but I am now getting the clunking when I put it in reverse. If I shift it slow it is usually fine but if I shift it like a normal person puts a truck in reverse it clunks. I have read about the slip joints needing grease but I am not sure if this would cause it or not. Any info would be greatly appreciated..

[enaberif]

ujoints in driveshaft

[ehjorten]

NP203 is a Chain-drive transfer case.  The chain does not have any provisions for a tensioner.  The chain has stretched and it is providing the slop!  If everything is good with your rear differential and propshaft u-joints are good, then it is simply this chain slop.  It won't hurt anything.  My '77 has had this clunk for more than a decade with no issues.

[Kimper]

Thanks for the tips, I am going to Crawl under it this week and have my wife HOLD THE BRAKES and put it in reverse and look and listen for if its a U joint, rear end, or transfer case

[enaberif]

no no no bad bad. just grab the shafts and move them around. they should be tight with minimal movement.

[Kimper]

Well I have grabbed them and they seem tight but the guy who do my rear end said one of the u joints were in backwards and he couldn't get to the zerk fitting to greese it if that matters??

[Captkaos]

Doesn't matter just means  you can service it.

[Irish_Alley]

transmission mount can cause a clunk if its bad