Dana Transfer Case Shift Fork

Does anyone know if there is a difference between the shift fork for the front axle with part numbers 18-66-7 and 18-66-8? I need to replace mine for my TC Dana 18. Mine says 18-66-7 and I found a NOS but it says 18-66-8. Would that one work? The other alternative I am considering is to run a welding bead over the worn out section and to resurface it. Thanks!

 

Since the fork is unusable in its current condition and I have nothing to lose, I decide to go ahead and run some TIG beads on the scored side and then machine to fit. BTW, does anyone have the gap spec for this fork on the collar? After some welding and machining, I started to adjust the fit with a file until it was spinning freely and mating with no interference. Since this fork is not hardened I do not see the problem with using it after this repair. If anyone has tried this or has an opinion, please let me hear it. My feeler gage says the gap is 0.095. I do not know what are the specs as I said before. It is a decent fit in my opinion, bu I've been wrong a lot before.

 

I don’t know why there is a cast number difference is but the 20 and 18 front output forks will all interchange.