'88 s10 Blazer:

when it comes to the tranny, i don't have any problems. I'm assuming (it's bad to assume) its the actuator to engage the 4wd.
the prob is, i got no idea where to start... than taking it apart of course

I need advice!!!!!

 

Welcome to the site.
'88 you say.
Floor shifter!
Does it shift into 4wdr?
a) No, you got linkage problems?
b) Yes, Shift it into 4wdr, put the truck in park, reach under and try to turn the front driveshaft.
a) Turns, t-case problem, or shift linakge problem.
b) Doesn't turn, t-case is in 4wdr problem lies elsewhere.

If you ended on a, post up.

If your on b. Follow along.
No doubt your problem lies in the vacuum system. There are three vacuum hoses atached to the t-case.
I) 1 provides vacuum to the t-case and is coming from the back side of the distriburator. Look for a connector. The vacuum comes off the intake manifold by the distriburator. Goes into the connector where it gets split to several places, one is your t-case, another is the heat=a/c controls, and the third place is the vacuum ball. Make sure all of the vacuum hoses are hooked up and not leaking. A leak in any of them will not allow you to get vacuum down tot eh t-case.

II) The second vacuum hoses hooked up tot he t-case is a vent line. Look for a tee fitting on top of the t-case. One leg of that tee will go to a second vent line on the t-case. The other leg will go up past the tranny dipstick tube and end near the battery. Should have a vent/air filter on the end.

III) The third vacuum line off the t-case goes to your vacuum control modual. This is located next to the battery, or under the battery tray. GM moved the location in later years. Its in either one of those places. Make sure the vacuum hose isn't leaking anywhere. Also remove the vacuum hose from teh vacuum modual. Push the diaphram in with your finger, put your thumb over the vacuum line hole and lt go of the diaphram. If the diaphram moves, the vacuum contorl modual is broken. If the diaphram doesn't move, you may have missed a leak in one of the hoses. Look again, better yet replace them all.

All new hoses and the vacum modual works, your problem lies in teh front diffrential. Post up.
If the vacum modual is broken, junk the vacuum system and install a Posi-Lok kit, or make one yourself.

Clcik me for homemade posi lok install.

Clcik the above link to see what I did on my '87 to install a posi-lok. Only reqreats I have is not using a rubber coated cable. Mine works, but at times it can be a bear to get engaged. It has never disengaged, just a pain to engage at times. But the link will give you an idea what the vacuum modual looks like, and how it attaches to teh front axle.

Got any quesitons. Post up. I'll get an email and try to check email at least once per day during the week, weekends I am usually busy, but will check if someoen needs help and lets me know in advance.