Hey guys I just swapped in what was sopposed to be a good used th400 into my 78 chevy 4x4 with a np203.

I have got the tranny fluid topped right up. When I put the truck through all its gears it wants to go forward. No reverse or neutral. I have adjusted my get selector at the tranny also. I also put in a new filter and oil.

Is there anything else I can check on this tranny? If not I guess I will call the guy back.

Thanks guys,
Matt

Does the tranny attempt to also go foward in park? If so, you may have a bent/sticking spool in the valve body. You could try rebuilding the valvebody, or getting your money back.

Hey Kilborg thanks for getting back to me.

The tranny does attempt to go forward in park like you say.

So do you think that if I take the valve body out of my other tranny that I pulled out of my truck that would fix the problem??

I will also email the guy I got the tranny from and see if he has any suggestions on a refund.

Thanks for the help!

Matt

I had this problem with my th400. I was playing around one day and all of a sudden i didn't have reverse forward gears were fine. I thought the guy that rebuilt it said i broke something like some hard part inside tranny.