Automatic extension clearance

What is the max clearance for extension and shaft on a 79 trans? Turbo 350 automatic. Mine has aprox. .020 play  

sounds like too much clearance to me...

on a turbo 350   you need an output shaft seal...  a tail shaft bushing... a tail shaft O ring.. (square cut usually)  a speedo oring and speedo gear seal...

and probably a trans mount..

with all the parts.. pull the driveshaft..  examine the yoke for finish on the outside... if you have notches worn in it.. you will have to get a replacement yoke..  and a new U joint..  or two...

you can support the transmission with a jack and a chunk of plywood.. so you don't tent the pan...  pull the crossmember the trans mount..   the speedo cable.   then the tail housing..

the important thing. after you replace the bushing in the housing..   you have to try it on the yoke.. make sure the yoke slides in through the bushing before you put the seal in...     then a tiny bit of grease or vasoline.. to hold the garter ring on the inside of the seal.. so it does not pop off when you drive it in...  

the parts are less than 15 bucks at most transmission parts stores...  add some more if you need a new trans mount..

i normally make a driver out of a long bolt.. 2 nuts and an assortment of flat washers...  some that fit tight inside the bushing.. and some that are slightly larger than the outside diameter...  with the bolt long enough to hold in your and  and hit the head to drive the bushing home.. then the seal after that..

wheel bearing race drivers can also be used..  using care not to mushroom the end of the bushing..

oh.. and the reason to make sure the yoke fits in the bushing..   its easier to trim the end of the bushing before you put the seal in...  this tiny bit of mushrooming does not effect anything.. but the yoke has to be free to slide..