[m2summit]

Hi I have a 71 Chevy 4x4 with a 3 speed standard transmission with a NP203 transfer case. My question is can you use the NP203 from the standard trans. with a 350 THM auto transmission and if so what adaptor will I need for the back of the auto transmission to make it fit. Thanks for any help

[F&J]

I haven't worked on the 203 full time stuff in 30 years

I did mess with a lot of 205s. On 205s the transfer case is identical from std to auto UNTIL you get into TH400.(which we don't care about anyways)

On the 205s, you needed to get the center adaptor for whatever trans you want to use. I would guess the 203s have the same situation; needing a different adaptor for the auto. I really doubt a 205 adaptor would fit, nor a 208 either.

Those 203s are really old and you may have trouble finding one? There were MANY more auto trans 203s compared to standards, so there must be some left somewhere.

[m2summit]

The 203 I have is part time as the front hubs are spicer locking type I am not sure but this should be factory installed. The front diff is a Dana 44 with 3:73 gears.

I was hoping it would work with a TH 350 I had if I could adapt it.

Thanks for the info

[F&J]

The 203 was a full time box. There were aftermarket kits to make it a part time. Not just adding hubs, it had parts that went into the large cover on the back of the box. One way to tell if it IS a full time without a full kit; Unlock the hubs and have someone watch (from the side), to see if the front shaft turns. If it turns, it is still a full time.

I could probably come up with the GM part number for the adapter if that would help. The part is most likely not available anymore, but Junkyards should have one.