4 wheel drive clunking

1 have a 1996 s-10 Bazer LT 4x4 4dr. Last year I put it in 4 hi during a snow storm and the right front wheel was klunking and intermitently surging. This year I put it in 4 hi and when I got off thr highway I was stopped at a traffic light and plushed the buttom for two hi, as I acellerated from the intersection there was a loud and heavy clunk. This klunk was so hard the truch shook so hard I thought somebody rearended me. I bout the truck last year and it has 120000 miles on it, The dash selecter is the three button 2 hi, 4 hi and low. what could have caused this problem?

The front axel actuater not locking the front axel in good is a good place to start.

It is part eclectric and part vacuum operater plus a pull cabel.
Always check all vacuum hoses and switches for good vacuum to actuator.

See if this helps.
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914

thanks for the info it will help greatly with the trouble shooting.
Ron

You are welcome and let us know if you get stuck on it or how it goes.
MT

That link you sent me also explained why My HVAC is only working on defrost and vent at the same time.
Thanks again
Ron