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Discussion Starter #1
I had a 72 short K10 with a 350/350 combo years ago, never should have sold it. But the time has come for another. I bought a 71 K10 with a 307/4spd a couple weeks after I found a nice rebuilt 70 402 motor and decided it was time for a Big Block shortbed truck.

I drove the truck around for a week and actually didn't mind the 4 spd but it leaks like crazy and I know they make fitting headers a bear. So I've been reading a ton while I've been tearing the truck apart trying to decide the best way to do this.

Here's what I think I know:
You can mount a big block in the stock small block location but will have to deal with clearance issues at the drivers side valve cover and the distributer (if HEI).

You can run the 4spd if you run stock BBC manifolds (with trimming) or Doug Thorley headers if you modify your Z bar and clearance frame rails a bit.

If you have a 350/th350/np205 truck, the swap is pretty easy if you do the BBC swap and swap in a 700R4 at the same time by keeping the transfer case in it's stock location and moving the front motor mounts (cross member) 2" forward to accommodate the extra length of the 700R4. This also gives the best firewall clearance.

Based on what I think I know:
I am planning on swapping in the 402 along with a 700R4 and a NP205.

What I think I need:
Auto Trans steering column (ordered)
BBC Motor (have)
Pulleys, fan, clutch, etc
BBC Radiator and fan shroud (ordered)
BBC Doug Thorley Headers
700R4 and converter
Advance Adapter 50-5900 (700r4 output shaft to np205, 27spline) (ordered)
NP205 27spline
Stock th350/np205 transfer case adapter (ordered)
transfer case shift lever

I have sourced the correct th350 to NP205 factory adapter from a 1970 K20. I have purchased the advance adapter 50-5900 700R4 output shaft. I have a quote from a local shop to build me a stout 700R4 for 4x4 using the above output shaft. I have the 402 BB sitting in the shop. I have an Auto transmission steering column.

Will my Rockwell transfer case mount/tranny cross member work with the NP205? or do I need to source a NP205 mount/cross member?

What am I not thinking about that I need to?

Anyone have any of the parts I am still looking for above?

12,348 Posts
Does that have the married rockwell transfer case? It might be the same if so. The 205 transfer case crossmember bolts to the adapter.

More than likely, you will have to modify a driveline or two but not really sure.

I do know that on my 72, I went from a 350 205, to a 465/205, and didn't move crossmembers or motors, but it was a small block.

528 Posts
That truck has a nice body, We have a 67 SWB 4x4 4 speed with a built 383 and that things a fast truck.
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