What transmissions will fit a 1987 el Camino with a 305 engine without altering the drive line

Stock transmission replacement will have no need for drive line replacement. Tremac transmissions sells a transmission made to bolt up to your engine and has the same transmission mounts so there is no alterations. If it needs a different clutch or bell housing, it comes with it. Also as in mine, the drive shaft needed to be shorter, so they sent one also. All parts needing to be replaced was sent with it. If you go with any other transmission change, make sure it does not require any changes or alterations. Do the homework first before slapping down the charge card or cash/check.