'89 S-10 Blazer 4x4 trans problem

Removed the transfer case from my 89 S-10 Blazer 4x4 (114k miles) to repair leaking seals. Put it back in and now the auto trans has a shift problem. Won't take up reverse at all but will take up drive. (When I put it in reverse, I don't hear the shift "clunk" and it sounds just like it's still in Park or Neutral.) However, even in Drive, it's slow to move (over-revs) and won't shift from 1st-2nd, 2nd-3rd, and 3rd-4th (O/D). I didn't take any of the internal parts out of the transfer case, such as chain or gears. Only took the case apart and re-sealed it. Was running fine before I took the case out. Electrical connector and vacuum modulator hooked up ok. Fluid levels in both transfer case and transmission ok. Transfer case shifts ok and 4wd indicator lights functioning on console. Driveshafts hooked up ok. Any suggestions?
Thanks!

Look for some broken vac lines.

Look for some broken vac lines.

Thanks for the info, BlazerLT.

I checked the vacuum lines but they appear ok. Are there any other possible causes (e.g. electrical connection)?

I did think of one peculiar thing when I removed the transfer case: over 1 gallon of fluid came out but I only put about 1 1/2 qts back in. I can't figure out where it all came from, since I filled the case back up (on level ground) until fluid just began dribbling out the fill hole. Not sure if this is related, but thought I'd mention it since it's the only unusual thing I encountered. BTW, the auto trans fluid level appears ok. I drained and refilled it; it held 3 pints. (I have the 4.3 liter V-6 engine.)

Thanks again.

You have a bad transfer case seal which allows transmision fluid to leak past its rear seal and into the transfer case.

This is a known problem and even mine had the same problem but it took 100,000 miles to get that high.

Just fill the trasfer case properly like you did and make sure the fluid level is fine in the transmission.

Remember to check the transmission at hot idle in park and with you foot on the brake go from park to 1 and back up to park holding for 10 seconds in each gear.

This is have you taking a proper reading with the whole transmission primed with fluid.

Now with the 4x4 problem, you probably have a bad vacuum actuator for the transfer case. This is also know to fial , swap it out.