1986 chevy 3/4 ton

i recently got a 1986 3/4 ton 4WD 350 ( not fuel injected) truck. the front axle doesnt have the things to lock in the hubs on the front axle for 4wd. also, in the cab the 4wd shifter only has 3 notches. one up, a middle, then a down (so to speak.) is it all time 4wd. if so how does that work. otherwise are they automatic locking hubs or something. ALSO. i put a rebuilt engine and tranny in it. the odometer reads 235,000 miles. is there any way to roll it back or can only dealers do that.
Thanks in advance. Chart

Illegal to tamper with a odometer reading
You can even get jail time out of it.

Most of them was a old style full time 4W setup.
You can put a lockout hub kit on the front axles but you need to put a change over kit in the transfer case at the same time for it to do any good.
MT

I had an '88 Blazer 4wd. It had the "auto hubs". Don't remember what the shift pattern was. They lock in when you shift to 4wd and drive forward. To unlock them you have to go to 2wd and back up (a real pain if you have a trailer hooked up). My old '78 Blazer has the full time system. It has a 5 detent shift pattern. 4low lock, 4low, nuetral, 4hi and 4hi lock.

I'm pretty sure your '86 has the "auto hubs". I'm pretty sure you can pull the "auto hubs" out and replace them with manuals, but you should talk with a good 4wd source to confirm.

If this is a Full time 4x4 truck, which it sounds like it is, It is not going to do you any good to change the hubs to manual lock outs. Your transfer case is still going to be putting power to the front axle, which is a bad thing if your lockouts are not locked. If you really want to get rid of this you need a different transfer case and front lockouts.

Don't mess with the odometer, big trouble man!