NEED help for my 77 blazer
 

I love my Blazer and now i dont know what to do, I was using it to pull logs out of woods with snow on ground, when all of a sudden I no longer have any forward gears, its an automatic it grabs in reverse goes smothly in park but drive ,2 and 1 there is nothing, I never had a tranny do this before any ideas or is it blown? I checked linkage and thats ok

It could be the transfer case, the chain might have stretched and wore the teath of the gears in the drive direction. Maybe drain the fluid and check for metal with a magnet and or check for play at the output shafts, this requires taking the drive shafts off the transfer case. This is just a guess.

sounds like you are going to need a rebuilt tranny