Go to; www.metkit.com/
and look at the parts, go to the bearings/pins and they list the mechanical tubing for the outer sleeves, the "moly" impregnated bearings and the correct under sized pins for the backhoe application. You just need to figure the sizes into your design and they will do special cuts/lengths to fit your design too if need be. It also needs to have zerk fittings on all the moving parts too so they can be greased with moly daily when in use.
I'm not using bearings on my FEL since it moves slow and the forces aren't really high. I figure to use good steel with a moly grease for the moving parts(so far thats my plan) I don't see any wear at all on my neighbors Danco FEL with no bearings or bushings so far after all these many years its been on his cadet 147. But i could change my mind during the process to hardened bronze bushings. But I think if i use 4140HT structural tubing and is thompson shaft for the pins which is case hardened on the outside it should last. We do have some choices for the FEL.