TH400 and NP208 Help!!

[kkyle69]

I have a TH400/NP208 setup and can't figure this out. Truck runs fine in 4-LO, but motor hestitates and stalls in 2-HI and 4-HI. Fluids are new and full. Is this a tranny or T-case problem. Any ideas? I don't want to pull unless absolutely have to.

 

[jays68yak]

hows the motor run in general? My 350 was a pig with that setup. Tossed it and put in a 454 TBI motor and didnt have that problem again.

 

[kkyle69]

hows the motor run in general? My 350 was a pig with that setup. Tossed it and put in a 454 TBI motor and didnt have that problem again.

the motor runs goods, I put a whole new top end in it.