As was said before, . they have been around a while, . . some converted by individuals, others by fire depts. etc. As far as swapping out your 402 for a SBC, that should be relatively easy. Your bell housing and transmission adapters will work, you may need to adjust motor mounts, and your exhaust manifolds will be different. You want to make sure you get all the pulleys and brackets for the SBC, because the ones for the 402 are different.