I found two Isuzu NPR trucks for sale. One has only the engine and the guy said it just quit working so they pulled the transmission. The other one runs but needs a fused link to start. They were use in a vending business so they were ran hard every day in Atlanta traffic(close to California rush hour). What would be some things to look out with these engines besides the oil and visual condition? I was thinking around 400-1000 price range but I do not want to over pay or get laugh at. The two trucks are 1991 models. I looked for some 91s on Google and did not find any to price compare. Thank you for any help.