Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

I have a 98 k 1500 4x4 5.7 Ext cab chev pick up.   It has been a super truck  almost 270,000 miles.   I bought it  brand new 97 and have been drivin it like i stole it its whole life.   165,000 miles out of 1st tranny(always well maintained) replaced with used (no rebuild) used tranny and worked perfect until now.    Truck takes off in 3rd gear with gear selector in drive or overdrive no difference.(very doggy)    does not shift into overdrive  once up to speed.     put gear selector in 1st and itll take off in 2nd.    tranny seems fine until it gets up to temp then problem becomes obvious    any help is greatly appreciated  

do a search for "sonnax". it sound like an afl valve problem. they explain it on their website. i thought this was my problem until i talked to a pro. he told me it would be the afl if it did this when it "warmed up".