I'm a new chevy owner and would like to make this thing go! It's a straight truck and has pot. trans is the 4L and would like to buy or rebuild the one in it. won't go in D. Both the engine and trans had been replace with a Late suburban. Discovered the trans linkage was wrong. The piece that bolts to the selector shaft on the trans was not correct for that year. Ordered the correct one from dealer for 8 bucks and awaiting its arrival. After installed I should check or do what? and I'm thinking the trans is **** up and could use a rebuild. Among other things the exhaust needs help so is the cat conv necessary and should I do If I remove?