Have a friend that has one made out of a used electric pole and two trees with a V in them. It does not set the straightest but I have seen him change many car/truck engines under that "natural" bridge. LOL I would be afraid to even walk under it and he will work all day under it.
Until a few years ago he used an old hay rope and a snatch block to lift everything. Little Ford tractor on the rope. It did not have working brakes. He just killed it in gear. LMAO.
He broke the rope and then went to CHEAP China cable come-alongs. HE is a regular church memeber. I keep telling him he is going to try out his membership if he keeps it up.