I am in the same "search" on my 48, but I fully expected a zero chance of any bolt in unless I pay one of the axle shops to make up a axle for me. They are out there I have found several but cost is not always agreeable.
Since I already have my front in disk brake conversion and still 8 lug, I want to keep 8 lug on the rear. It would be cheaper to switch to 5 or 6 lug front and back with better options but I wanted to keep tow/haul level up and option for stock wheels.
As for 8 lug choices not in any order just some of the better options, GM 14 bolt corporate axle, American AAM 14 bolt 11.5 axle.
With two outside possible options in the Dana 60 and a Eaton from a newer year PU.
The GM has a great following and easy to get one of the four options but to my checking so far the C&C version is closest to size, but is a dually axle that would result in issues if you want SRW but most common finding in drum brake. The AAM is a nice unit and can be found easy in disk brake set up and easy to modify.
All will as stated by Joe H, you will need to change spring perches at minimum if your keeping stock spring types (easy way). Or need to change spring frame towers for 2" if you want newer spring types (more options).
Axle perches change out is more a test of patience then any thing else (if you can weld), most is care in removing old and extra care in geometry/placement of new.
Going to a newer year Eaton sounds great getting newer (easier to find)axle parts but issue still exists on axle width.
keep posting what your going to do and how it progresses. I do the same.
