Dana 60 - Factory 5 bolt pattern ?

Find a 70 on up, ford 3/4 d60 with trac loc and 4.10s. Cut the ends off your 8 3/4. Cut the ends off the dana. Measure and fix 8 3/4 ends to length and weld together using the 8 3/4 axles.
You have the price of the dana and the cost of the 8 3/4 that you are using for part. And cost of having it welded together. Or buy new ends for about $80 instead of cuting up the 8 3/4. New spring perches are $15 if you don't use the ones off the 8 3/4.
How much this cost depends on what you paid for the axels to start with.
Dana $150
8 3/4 b body axels and brake assembly. $150
new axle ends and perches $100
welder doing the work. $250
total. $650

It can be done for less by shopping around for good deals.