Gears, bearing, seals, labor

[DANTIP]

I am trying to compare ideas to reduce highway RPM and want help determining the cost to change gear sets back to the original 3.08:1 ratio in my 72 C-10. I suspect a PO put 3.73:1 gears onto the original 3-series carrier (because the code on the housing is correct for 3.08:1). If they didn't change the carrier I should be able to change the gear set out and use the existing carrier. I would probably order a complete kit including seals, bearings, gears and install kit. I am hoping to get good ball-park cost estimates to do this two ways. First price is if I do the work myself, and the second price if I have it done professionally. Lastly, if I need a carrier and opt for a new Eaton 3-series posi how much labor would the carrier change add if any?

Thanks!