the car is an s30 that has an sr20det engine i put in it. I just recently got it going and noticed after about 300 miles my tranny was leaking oil from the rear seal the driveshaft goes in. i pulled my new shaft out and noticed it was pretty scarred where it rides on the bushing in the transmission. the bushing in the transmission looked the same. my driveshaft looks to be pretty straight but not perfect. this defidently is not normal wear and tear scarring through chrome it will catch your finger nail if drug across. it is possible the the transmission had prior damage to the bushing which damaged my drive shaft or there was debris in there. it also ran low on oil but for no more than 30 miles. I just rebuilt my transmission and put a new yolk on the driveshaft. I am just afraid to drive it and have the same problem. the only other idea i had was maby too much driveshaft angle causing vibration. i didnt notice any crazy noise while driving but keep in mind i have solid diff mount and no interior or windows so there were all kinds of noise. Anyways what i am trying to find out is what can cause scarring on a driveshaft yolk?