K20 transfer cases.

[Ziegelsteinfaust]

I know the 203, and 205 are common in the year trucks I just bought. 1973.

But what about the 208. or is it a latter year unit.

I pretty sure one has to likely be a 205 if stock due to the 4wd levers it has.

Any other transfer cases that are likely to of been used?

[Maxxd07]

It will be a 205 if it is part time 4wd. The 203 is a full time transfer case unless someone put a part time kit in it. If you have lockouts on the front and it has 4 hi, 4 lo, 2wd and N on the knob it is a 205. If the knob has 4 lo, 4 loc, N, and 4 (not sure on the normal driving position) it would be a 203. 208s didn't appear until the 80s.

[andrewmp6]

It could be a np203 or maybe a np205 the np208 was 81 and newer.Look on the t case for a tag that will tell you what it is or post a picture we can id it.

[ryanroo]

If it hasnt been messed with, it will be a 205. 73 was the last year(until 1980) that ll 4x4s had the 205. in 74 all of them had 203 unless ordered specifically with part time 4x4. then after that i believe the manual transmissions had 205 and the autos had 203. untill 1980 when they all had the 205 again. after 80, the half and 3/4 tons had 208s and the K30s had 205s

[doubleclucker]

Easiest way to tell GM SQUARE transfercases ;Without getting your back dirty...
If shifter sticks straight up and is flat NP203-73-79 (cast iron)
If shifter sticks straight up and is round NP205-73-91 (cast iron)
If surrounded by a little console and shifter is pointed towards firewall NP208 or later NP241- 84-91 (all aluminum)