Previous answer: Properly equipped, wouldn't recommend any heavier than 1000 lbs
Edit:
I don't' know the rated capacity but back in the day my family towed a camper identical to this round trip 600 miles every summer, mostly highway driving, some Pennsylvania "mountains":
http://www.sunlineclub.com/forums/f78/1988-saturn-t-1550-linwood-mn-4499-sold-11388.html
Total estimated towed weight was about 2300 lbs not counting about 800 lbs passengers and cargo in the car. 1990 lbs (empty camper, source above).
We towed w/ a 1984 & later a 1987 Celebrity, both station wagons & both had the 2.8L V6 engine, we added Class 3 hitch, lighting wiring & trailer braking system. The 1987's rear springs were upgraded to heavy duty, they helped dramatically. The only problem we ever had was overheating once on the PA Turnpike on a 100° day.
help
go to chuck's Chevy pages .com the answer should be there.
The spark plug gap for a 1986 Chevy Celebrity with the 2.5L 4 cyl engine is .060".
Seriously, Just don't. You will ruin it.
Does your 1986 Chevy Celebrity have the 2.5L 4 cylinder engine or the 2.8L V6?
If it is a 2.8 it has 2
18-25 if your not towing anything
3500lbs manual, 2000lbs auto.
Here's a link to the answers most are looking for. It's a brochure for the 1986 Blazer/Suburban/Jimmy's. Looks like 6000lbs for gasoline engines, less for diesel. http://www.coloradok5.com/brochures/1986/
GVW is listed on the sticker in door jam
I found one source that says a 1986 Chevy Celebrity has a curb weight of 2714 pounds. Different options would change that weight.
Please clarify your question as in front or rear axle.