Well now Burgie you can either just back the truck up a bit and learn something, or ya can get all head up. I really don't give a rusty rats *** which way you go, but I took the time to scale your picture and allow an Old Fart who has put together a hell of a lot more iron together to acquaint you with reality.
FACT 1, your design is a 3rd class lever ergo, presuming your jack can produce 8 ton of force, the maximum lift at your hook would be 1/3 of that force or 5,333 pounds.
FACT 2, your stinger made of 3/16 wall tubing will NOT support 5000 pounds. Neither will your horizontal legs, and those casters will be crushed long before you get near 3000 pounds.
FACT 3, your reenforcment from the back crossmember to the boom is mislocated and will contribute to the boom bending if and when you get a heavy load on the stinger.
FACT 4, The connection between the legs and the crossmember is insufficient. 3/16 wall tube will yield damn fast under force around a bolt unless the boltholes are reenforced.
FACT 5, Your method of attachment between the stinger and the lift chain is dangerous.
The paint job looks nice though.
Now, like I said, I don't give a damn, so you can either ask for help to retrofit the contraption, or you can get hurt bad using what you have. That part is up to you.
