i'm running redrilled MJ leaves with the rear axle about 1" back from stock, so needless to say the factory shackle mounts were about as much use as tits on a boar hog.. and i needed a new rear bumper/tire carrier (to come later)
1st i cut out the rear facing sheet metal between the 4 bolt mounts for the original rear bumper, part of mine was already trashed due to the tire carrier i had fabbed previously was pulling the nut strips through the sheet metal on the passenger side.
cutting this sheet metal away allowed me access the inside of the "frame-rails" it measured approximately 2-1/4" x 4-1/4" PERFECT for that i had some 2x4x1/8" tubing to use
for starters to make mounts for the bumper i cut 2 pieces of the 2x4 about 12" long,
on the passenger side i had to deal with the PITA factory nut strip for hitch mounting, but after that little fight i worked both pieces into the insides of the "frame-rails" and marked the depth at which i planned for them to seat into the frame, on the drivers side the fuel filler neck permits about 7" from the rear sheet metal, so that as a baseline i pulled up the rear cargo area carpet and made some marks and made marks on the outsdie edges of the 2x4 tubing for where the upper shackle bolts would hit them (if they're tightened inward, you must loosened them in order to insert the tubing into the frame rails)
then i cut some shims from some 2"x1/4" flat bar and tacked it to the outside of the 2x4 tubing and also 1 piece along the bottom. i positioned the outside shim so that the mentioned upper shackle bolt would strike it aprox at its center thus giving more support to the wall of the tubing.
once i had the mounting tubes inside the frame rail and the shackle bolts tightened and holding them i tacked into the floor of the cargo area a 4"x1" plate with 2) 1/2" holes, then drilled through the said holes throught the tubing and out the bottom of the frame rails.
since my buper design incorporated new rear shackle mounts i also cut some round tubing to act as crush sleeves for the original shackle bolts to be tightened against the tubing.
the rest is pretty self explanatory,
i cut a length of tubing for the main bumper tube, clamped it in place and tacked it on then pretty much did the same for the shackle mounts then pulled the whole thing off as a unit and finished out the welds and gussets

1st i cut out the rear facing sheet metal between the 4 bolt mounts for the original rear bumper, part of mine was already trashed due to the tire carrier i had fabbed previously was pulling the nut strips through the sheet metal on the passenger side.
cutting this sheet metal away allowed me access the inside of the "frame-rails" it measured approximately 2-1/4" x 4-1/4" PERFECT for that i had some 2x4x1/8" tubing to use
for starters to make mounts for the bumper i cut 2 pieces of the 2x4 about 12" long,

on the passenger side i had to deal with the PITA factory nut strip for hitch mounting, but after that little fight i worked both pieces into the insides of the "frame-rails" and marked the depth at which i planned for them to seat into the frame, on the drivers side the fuel filler neck permits about 7" from the rear sheet metal, so that as a baseline i pulled up the rear cargo area carpet and made some marks and made marks on the outsdie edges of the 2x4 tubing for where the upper shackle bolts would hit them (if they're tightened inward, you must loosened them in order to insert the tubing into the frame rails)
then i cut some shims from some 2"x1/4" flat bar and tacked it to the outside of the 2x4 tubing and also 1 piece along the bottom. i positioned the outside shim so that the mentioned upper shackle bolt would strike it aprox at its center thus giving more support to the wall of the tubing.
once i had the mounting tubes inside the frame rail and the shackle bolts tightened and holding them i tacked into the floor of the cargo area a 4"x1" plate with 2) 1/2" holes, then drilled through the said holes throught the tubing and out the bottom of the frame rails.

since my buper design incorporated new rear shackle mounts i also cut some round tubing to act as crush sleeves for the original shackle bolts to be tightened against the tubing.
the rest is pretty self explanatory,
i cut a length of tubing for the main bumper tube, clamped it in place and tacked it on then pretty much did the same for the shackle mounts then pulled the whole thing off as a unit and finished out the welds and gussets