I had a choice to rebuild the engine, buy a used engine or buy a factory new engine. I chose to replace the engine with a new 1995 spec factory engine. The transmission in the early twin turbo Zs were not built strong enough to handle the Twin Turbo's power, and my transmission went out at about the same time as the engine. I replaced the transmission with a factory 1995 spec rebuilt transmission. The work was completed by United Auto Sales New Castle, DE. Back then the total cost was $12K.