98 Truck questions

I've been looking for a truck that was priced good enough for me to buy as a vehicle to pull my car and trailer. I've found a 98 ram standard cab shortbed with 137000 miles but no rust. The old man that owned it painted the bottom below the trim and just above the wheel wells with what looks to be a bed liner type paint. Seems to have protected it very well. So far i've only seen pics but the seller has sent me 30 or more. Its a 5.2, 4wd automatic. With the mileage im assuming the trans wouldnt handle much towing before a rebuild. My trailer and car I would guess to be around 5k lbs maybe a little less. The person that has the truck got it in a deal for remodeling this guys home so he has no use for it. I made an offer but someone else is looking at it tomorrow and I cant get there until Tuesday. He said if it doesnt get bought tomorrow he would accept my offer. Of course I told him I would first need to check frt end for bearings and ball joints along with motor and trans. What are your thoughts on trans and motor with the mileage it has? Also anyone else towing with a 98 short bed? I hope to find a tag on rear to see gear ratio. Did they put ratio or an ID# on tags? What other concerns other then normal stuff should I check before buying? As I said body looks in good shape with no rust other than the ugly paint.
Thanks, Rod