Looking at an 86 half ton chevy. I believe it's the scottsdale? It comes with a 305 v8 with locking hubs. Where can I find out, or does anyone know what axles come on it? Are they strong enough for 36 iroks? It's currently running 35 bfg all terrains on 6" lift. What auto trans and transfer case did it come with and how strong are they? I'm looking to gear it down (4.88's?) and run the 36 iroks, possibly w/lock rite front and rear. It will not be a daily driver but a beater for sand, mud, and trails. I'm not looking to put a big block in it or anything too extreme. Anything I should look for in that year or to stay away from? I might make an offer tomorrow, please help.

86 should be the last year before tbi. Easy carb upgrades without computer hassles. A 1/2ton will most likely have 10b front and rears. There are mixed opinions about the 10b's, but the general consensus is that if you drive reasonably, you'll be fine with 35's and under and they are readily available for replacement parts. The 305 is a weak engine in my opinion. Not enough motor for a full-size truck. If the trans is automatic, it's probably a 700R4 and mated to an NP208 transfer case. The 208 is shifted via floor selector and has an aluminum case.

Here's a link to some Blazer specs for different model years:
http://www.coloradok5.com/specs.shtml

Alot will apply to the trucks too. Check around that website for more info.

I have a 76 plow truck with Dana 44 axles and 4.10 gears I could swap out if they are quite a bit stronger? I also can get a 350 for cheap from some friends down the line if needed. Do you know what factory gearing might have come in it? Will the transfer case hold up? I could swap the transfer case from my 76 if it's stronger, I think it's a 205?

My 208 has held up just fine with a few leaks that have been dealt with. The 205 is considered stronger because it isn't aluminum. Also, you can convert the 205 to eliminate the slip yoke. There is no such kit available for the 208. I wouldn't bother with swapping out the 10b for the D44. To me, it seems like too much work, for no advantage. They aren't as readily available and aren't really any stronger. You'd have to change the brake lines too I believe. They both use the same design for steering components though. Definitely shoot for that 350. As far as gearing it could be anywhere from high 2's to high 3's from the factory. 3.73 is common if my memory serves.

Thanks for the fast replies. Sounds like I'll just run the stock axles until I break something then upgrade.

I just spoke further w/owner and he stated it is currently not geared down. He said it really has a lack of power and I'm sure some of it has to do with the 305. I'm wondering if it would be worth my while to swap axles with my 76 3/4 ton now since it has 4.10 gears? I'd be looking at 300-400 for new gears for the 10 bolts. I'd still have to buy new rims that were 8 lug though. My 3/4 ton is a 76 and I was told it's 44 front and rear w/4.10's. Is there a way to swap my 6 lug to 8 lug and not have to buy new rims?

First off, If your using this as a sand, mud toy, leave it TBI. Carbs dont like off camber too much. Secondly if the axles need to be regeared them upgrade to bigger axles, especially if you already have them .

Your lack of power probably stems in large part from running 35 in tires on a axle that more than likely has 3.08:1 gears. Which is too high for running tires that size.