Possible SBP to LBP adapter group buy?
Any more than $100 a pair, and you'd be a good share of the way towards a set of Dr. Diff's 7.25 axles with true 5x4.5 bolt pattern and the correct center register; a much better solution.
Mopar Axle Pkg 7 1/4" A-Body 5X4 1/2" Bolt Pattern (pair)
I'm not a big fan of spacers/adapters either. If you're planning on running a big wheel/tire combo on the rear, you'll need more backspace with the adapters and then when you get a real bbp rear it could be too much and you may need to get different wheels again- negating any potential savings with the "temporary" spacer/adapter solution...
except his axles won't work with my 1976 SBP rear end, and you either have to buy different drums, or modify yours. it says that you can redrill your existing drums, but doesn't mention the drum center bore. if that's the case, then these axles wouldn't have the correct BBP register, as your existing drums center hole is 1/2" too small.....
at $300 for new 7.25" axle shafts ($420 with drums), you're WELL on your way towards a much more durable ford 8.8 axle, whether it's a direct pull out of a ranger or explorer, and if you decide to do the 2 RH axle shafts and narrow the explorer axle. They're about $200 out of yards around me. You do have the added cost of driveshaft shortening and shock plates (I haven't looked closely to see if the 7.25" shock plates can be slotted to fit the ranger's 2.75" U-bolts), and the cost or time/hassle of cut/weld perches, get parking brake cables to hook up, etc.
1" spacers turn my 57.125" rear axle into 59.125" mount face to mount face. that is 5/8" wider than a ranger axle or 1/2" narrower than an explorer axle, and 3/8" narrower than the suggested '66-67 B body rear end swap for dusters/dart sports/demons. It gets the front and rear track closer to each other. Measuring my duster, this width allows 235's out back with stock offset (+1/4") wheels before you have to start thinking about rolling the 1" wide fender lip at all, and 275's (maybe even 295's) with +30mm offset (up to 2004 mustang) wheels.
In this thread, I don't really want to get into the discussion of to use adapers or not, or alternatives to get BBP in the back. It was intended to gage interest, and if there is enough interest out there for what I'd call a "higher feature" adapter to actually make them.