I am getting ready to do the same for a 59 GMC. Front spring centers are 32" on the 59 -- not sure what a 46 is off hand. But Dana 44 and gm 10 bolts are 32" also for front.
I have a matching front/rear out of an 85 1/2 ton ---- GM 10 Bolt and 10 bolt rear I will use. You can use your 12 bolt as long as you have matching gear sets for front. You may want a right hand drop transfer case. If not rock climbing or mud bogging -- I like the np208. Can be mounted to a 350TH, 400TH, sm465 stick, 700r4 --there may be other custom adapters for other trans. Input shafts may differ with trans so be aware. I run a np208 behind a 700r4 in my 67. I will run a np208 behind a 350Th in the 59.
Frame swap can be done also ---- maybe an S10 reg cab long bed 4x4. Not sure on a full size. Keep all the s10 running gear ---- hopefully use 4.3 engine also.
I like this stuff.
