I have a 92 sierra
standard 2 wheel drive
4.3 I need to know if it's
safe to tow a car on
dolly. Im towing a
mercury sable which is
roughly 3800 pounds
See this, be careful, it's not advisable to tow more than 75 percent of the vehicle tow capacity.... Your Mercury Sable at 3800 pounds is 76 percent of the total tow load... http://trailers.com/tow- capacity/1992_Chevrolet_GMC_C1500_Pickup_(2WD)_350.html
If I were you, I would pay very close attention to the requirements on the axle, transmission cooler, etc.
Search GMC Sierra 1500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
GMC Sierra 1500 Experts