SM465 Can't get it to go into reverse

[82 Silverado 4X]

I ran into a problem on my 82 4x4 tonight. A wire under the hood burnt off leaving me unable to start my truck. Since I was on a grade I figured that I could coast it to get it moving and catch it in gear. When I let out the clutch in 1st gear it made a nasty sound but it didn't start. I coasted it again but put it in 2nd gear this time and it started. When I tried to put it in reverse to back up, the shifter wouldn't go over far enough to the right to get it down into reverse. All forward gears are fine.

Anyone have any ideas what I broke and any recommendations on what it's going to take to do the repair?
Thank you