How much T/Case gear play is acceptable?

[philippe]

Hello, after two years in the shop, I've finally got my '87 EFI RR back.
I know that I should expect some driveline backlash with an accompanying 'clunk' but my car seems really bad. It seems worse when slowing down as the autobox changes into 1st.
I also have a '89 EFI RR with the BW T/C and this car is clunkless in comparison.
On my '87, if I grab both propshafts and turn the rear one, I have 15-20mm of slack (outside of handbrake drum turning in relation to the fixed backing plate, in High Ratio). This seems excessive (my '89 has about 5mm). If I do a repeated accelerate/ liftoff/accelerate, I get both axles and the T/C clanking away. In Low Ratio mode the clanking seems less noticable.
It also seems to clank less when cold..
I had a really bad shudder/vibration problem which has been improved with a full suspension and steering rebuild, but it came back again. I pumped the propshafts with grease and the vibration went away.
I with rebuild both propshafts as a matter of course, but do you think the T/C is showing excessive play?
Many thanks for your help and Christmas wishes to you all. Philippe

[carlosz]

the b/w tcase uses a chain drive and that diminishes the slack and thump associated with gear mesh while the lt 230 uses gears, after a while they develop a small gap due to wear and tear and that is what causes the thump. you can overhaul it in order to return to factory specs but eventually afer some 40.000 miles the wear will set in and the noise and thump will return............it is the nature of the beast.