GMC 1998 Savana Van Owner's Manual page 194

You should use DRIVE (D) (or, as you need to, a
lower gear) when towing a trailer. Operating your
vehicle in DRIVE (D) when towing a trailer will
minimize heat buildup and extend the life of your
transmission.
Three important considerations have to do with weight:
the weight of the trailer,
the weight of the trailer tongue
and the weight on your vehicle's tires.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull a
trailer are all important. And, it can also depend on any
special equipment that you have on your vehicle.
The following chart shows how much your trailer can
weigh, based upon vehicle model and options.
Model Engine
GlOOOO 4.3L
5 .OL
5.7L
G20000 4.3L
5 .OL
5.7L
G30000 5.7L
6.5L
7.4L
Axle
Ratio
3.42
3.73
3.42
3.42
3.73
3.42
4.10
3.42
3.42
3.73
4.10
3.73
4.10
3.73
4.10
3.42
3.73
4.10
Max. Trailer Weight
(lbs.)
4000
4500
5000
5500
6500
4000
4000
5000
5500
5500
7000
5500
7000
6000
7500
6500
8000
10,000
(kg)
(1816)
(2043)
(2270)
(2497)
(295 1)
(1816)
(1816)
(2270)
(2497)
(2497)
(3 178)
(2497)
(3 178)
(2724)
(3405)
(295 1)
(3632)
(4540)
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