I've owned a 92 2wd magnum 318 auto, and an 89 w100 318 auto.

I picked up a 1991 W250 360 manual tranny, single cab long bed, for a killer deal and it is by far my favorite I've owned yet. The engine runs great, tranny and clutch shift good, 4x4 works fine, and it rides great on the highway as well.

I would like to know more about this year. Like how do I find out what gear ratio I have in my differentials? Is there any performance mods that don't require messing with the ecm? What type of power steering fluid does it use, what type of brake fluid? Any issues this year of ram is known for? What about this year of 360? I already know about reinforcing the steering box and adding A borgeson shaft, I did that on my 89 w100

Sounds like a beast. Those engines have roller cams, timing chains, iron intake mans and run a long time. probably 355 gears. The granny in the tranny in low transfer case gear will be just strong as you'll need for anything. I assume it's solid as you are in Wash.? Lucky you, and maybe the roof will hold up for you(rust). I would consider putting manual front hubs on it and lock the axle disconnect fork somehow.

Its a TBI engine so not much for performance out there. I had some luck with a dual snorkle air cleaner off a 88 318 Van and increasing the fuel pressure by switching to 6 an feed and 4 an return lines. That engine had 308 heads, but cam is so small, can't take advantage of them. You may have dual air pumps and they are a significant parasitic loss

Gears are either 3.55 or 4.10s. Tags are bolted to as cover bolt on each diff. If GVWR is 7510, should have a dana 44 HD up front and a dana 60 out back, but maybe a 9 1/4 if factory was trying to get rid of them.

Power steering fluid can be regular fluid- nothing special needed, just clean. Brake fluid is DOT 3- again just leep fresh and clean.

Nothing special or unique about a 91- I would consider treating the roof interior though. Rust is relentless in that area. Heres how i did it
http://ramchargercentral.com/mopar-trucks/1988-w-100/

I removed the air pump. it had 2 large tubes heading back towards the exhaust behind the engine, not into the heads like I had heard they went. On fords, the air injection went straight into the manifolds, and those were easy to seal when removed. I was told on a MOPAR 360, the air injection goes into the heads, but I cannot see where, unless its the back of the heads which I cant see (havent spent to much time searching.)

I removed the pump, pulley and brackets, plugged the vacuum line and temporarily blocked the tubes until I can get under the truck and see where they lead.

The power steering pump squealed like crazy and when I checked it out, the belt was very loose. So I got a new belt, and after I removed the smog pump and related brackets, I changed the belt on the power steering pump/reservoir and properly tightened it, and topped off the fluid. It was silent for a day, now it makes off and on squealing noises, especially when the engine hasnt fully warmed up.

Is it possible for the pump itself to be making the squealing noises, or be so worn out that it doesn't spin easily therefore making the belt rub against a stiff pulley?

Its possible that the pulley on the power steering pump is bad. the belt is suppose to run on the sides of the V, not at the bottom of the groove. If the belt has been run loose for some time, the sides of the pulley wear and the belt no longer grabs on the sides. This lets the belt bottom on the pulley and only drives off the very bottom of the belt, and it will slip until everything warms up. Eventually, the belt will slip all the time. If the belt is very low in the pulley, the pulley needs to be changed.

The air injection ports on the 360 heads are under the exhaust ports in the heads. If the manifolds are not removed, the ports in the heads will remain covered by the manifolds. If you cover the large holes where the emission tubes connect to the manifold, you will not have an exhaust leak, as long as the manifold to head is still sealed, and the manifold is not cracked. If you pull the manifolds off, the ports in the heads, under the exhaust ports needs to be plugged. Those holes are 1/4" in diameter, and run up into the exhaust port in the head, about 1/2" inside the manifold surface. Gene