I'm looking to buy a 1980-1991 K5 Blazer soon. What are some of the major differences in those years and what are some common problems that they have?

depending on the particular one i buy, i may need to put in a new motor and tranny. What motor and tranny combo should i get?

What I want:

-small block 350 (under $2,500): 250-300 hp what is a good tq number?
- 4 wheel drive of course.....so whatever tranny works with that
-Automatic trans. 700R4 maybe?
- 6" lift
- 35" tires
- mostly street driven.....occasional off road....but nothing big time.

any important questions i may have forgot to ask?

 

try to get a 91 or 92... the have the better looking frontends... the drivetrains are almost exactly the same.... '87 was the first fuel injected year... You want an '87 up motor if you want to run a stock motor. The best combo I have seen in those trucks is simple.... 350-383, TH400, 4.10 gears and 35-37 inch tires... make sure you get an injected motor though. TPI wuould be nice out of an IROC comoro or something... look around. those parts are everywhere....

 

91 would be nice, but i don't like the 92, i like the older style.

 

K5's are sweet. I've had two of them in the past (81 & 88). About the only real problems I had with mine was blowing the rear end up. I went through 2 or 3 sets of gears on the '81 and pretty much exploded the diff & axles on the '88.

Just look out for the normal things...rusted body panels, cracked transfer cases, cracked frame where the power steering pump is mounted, check for leaks on the removable roof, etc.

I think 1985 was the year they started putting a bunch of emissions crap on the motors and maybe cats too. This site will give you alot of info:
http://coloradok5.com/specs.shtml
http://coloradok5.com/

As for motor, you could look into a LT1 swap.

 

The absolute best K-5's are the 70-72's completely removable top to the windshield... good luck finding one thats not a rust bucket though and not spend 10G's