I have a 1989 dodge d350 dually dump truck with a 360 v8 and a 4 speed manual with airbags and I was wondering what the towing capacity would be for trucks like mine?

 

Do you know what gear ratio your rear end has? Is your transmission a regular 4 speed or does it have a "Granny" first?

 

I have the "granny" first because in first it don't go much faster than like 5 mph or so and I have the 4.10s I think, I'm not to sure, the engine revs a lot and it don't go much faster than 60-65mph and the engine is screamin.

 

Definitely 4.10 if not 5.88. My '52 B-3-PW had 5.88 gears and that flat head was about to throw a rod at anything over 40. It would run 30 all day. Depending on your hitch setup, the type of hitch itself (equalizing or not), ball type or pintle hook and so on. I'd say you can pull 10,000 easy. Much more than that, you'll want brakes on the trailer and a brake controller on the truck. I'd say maximum tow capacity will be around 14,000. However, considering the age, I'd stay below that.

Look around on your truck. On the rear end, there may be some tags. One of those may tell you the gear ratio. I always replace them when I open a rear end but some people don't and sometimes they rust away. There should also be a decal in the drivers door jamb. Either on the door itself or on the body frame of the opening. This will give you details on the axles and such. There may also be a sticker either in the glove box or under the hood.

 

this is actually some really bad advise. ideally you want trailer brakes for anything over 2-3000lbs. you want the truck to weight at least 10% more than what your towing without brakes and even then it would likely be hard on the brakes. 10,000lbs is likely twice what the truck weighs and would require trailer brakes in good condition if you were going to try it.

i would guess about 8-9000lbs max with trailer brake. i know i was pulling a 5000lbs trailer with a stock diesel d350 a few weeks ago and you could definitely feel it when taking off 1st gear.

 

This link says 8700# for a 1990.
https://www.edmunds.com/dodge/ram-35...eatures-specs/

Since its difficult to find properly vetted info, what you need to pay attention to is your trailer hitch rating, tire capacity, and meeting trailer brake requirements.

edit: You may also have to upgrade your driver's license to go beyond 10k# (depending on your jurisdiction.)