Rear end question

[mcfarlnd]

I was quoted today $850.00 to have my current rearend narrowed.....So, I need a cheaper solution (if possible) for a rear end. I have a bagged 61 stepside with a 78 C10 front end and currently have the 78 C10 rearend to install. My problem is I'm getting Eagle 227 20x10 wheels with 5.50 backspace and they simply are not going to fit because the axle is too wide. Are there any 5x5 narrower rearends from another vehicle that I could use? Or a good alternative? Open to suggestions except changing wheel backspacing is not an option.