i worked on one of those aluminum 4.1 caddys for a freind . it had a massive oil leak that came on suddenly. i felt obligated as i gave it as a gift.i replaced the rear seal[major pain], and it still leaked[more major pain].i could not see where the oil was coming from, so i ran the engine without the flywheel and found a crack in the aluminum 4 inches above the rear seal at the back of the block[super ,super pain]. it did not show until the engine was running. so i got another engine, no oil leak, yea yea!. he drove it a week, then more pain. crack in head over exhaust port. no more pain, called salvage yard.