I do need info on a purchase I made several years ago for a 73 1/2 ton Sierra Grande for 350 bucks. I was going to put the motor in my 78 3/4 ton Scottsdale but I found a 427 for that. So now I have a stock 73 with the factory installed 454 with 76500 miles on it. Yes it has rust in all the typical places but runs and drives great. Serial #TCZ143F729481. I found a 73-87 truck spec sheet but it has no Z for the 3rd letter in a half ton which would indicate it being a BB. Any info would be appreciated. I'm not sure weather to sell it or restore??