Hello everyone! I have a few questions. First and most important... I have an 87 K5 4WD 350 5.7L Most often than not, when the rear wheels are spun it will pull to the right VERY bad. If you turn left while it's pulling the tires will make a "squalling" sound. Once I turn a hard right, a LOUD clunk will sound and everything is fine again. This wouldn't be too bad if it wasn't for the fact that it will occasionally do it for no apparent reason while traveling at 70mph down the freeway! Scary Feeling! If you’re not on top of it you'll sail across a lane in a heartbeat. Any Ideas? I have heard everything from rear diff - the rear spring pin sheared off - to one of the front hubs locking. This truck is ALL stock. Still has the stock shocks on it. 220k miles. Runs pretty good considering. First question.... Any ideas/suggestions on the above? Second... I have a crack in the right exhaust manifold. I JB Welded it over a year ago, held great until I replaced plugs and put a K&N air filter in. I got on it a little hard and blew the JB Weld out. Replaced it and about a week later it blew out again. Now my dilemma. Should I go with headers, or stay with stock manifolds and just go with better exhaust and catalytic converter? A guy on another board said that headers for "most" people are too big a pain, with excessive heat, torqing head bolts, etc. Not to mention costs! I can't find used manifolds anywhere near my home, and one from the dealer (if I remember right from last year) is like $220! Anyway, any input would be appreciated! BTW at this point I don't do much off-roading, I need to replace a lot of stuff before I'm off-road ready... Glad I found this place, I frequent another board about ak47's and they are a wealth of information on ak’s, as this site seems to be on Blazers... Good to be here!