Chevrolet Repair: 700r4 transmission, k5 blazer, transmission expert

Question
Hi,

I've got an 86 K5 Blazer, 305ci 4wd.  Just had the tranny overhauled ($1000.00) about 2 years ago.  

Here's the problem... when its in OD everything shifts fine and runs great.  When I manually shift either 1,2, or D the tranny slips real bad and my blazer barely moves along.  When I put the shift lever back to OD, everything runs fine.

Some friends have told me I need a new valve body because thats the problem.  I guess it wasn't serviced at all when I had the transmission overhauled.  Can I purchase just the valve body (if thats the problem) and just install it myself?  I do work on my cars but have never been inside a transmission.  

Can you help me with some advise?

Thanks,

Mike

Answer
Hi Mike,
I have overhauled a few transmissions, however, I don't consider myself any kind of authority on them.
But before I ran down to buy a valve body, I think I would try to hold the shift lever about half way between two gears, and see if it might be a linkage adjustment, or detent adjustment required. It may be just barely opening a valve port.
If that doesn't seem to make any diff, at least ask a transmission mechanic.
You could easily change the valve body, but there are some balls that need to be placed in the correct places. If you do decide to remove it, here are some tightening specs I found.   

http://ls1.fbody.com/specs.html


It would surprise me to see a valve body "go bad" after working fine for two years.
See if there is an all expert transmission expert.
Good luck,
Van