83' gmc rearend questions?

[RapidRide2]

I have not purchased nor seen in person an 83' 1/2 ton gmc sierra 305ci. 700r-4(plan on going bowtie overdrives eventually) From pics the truck seems extremely clean. I have a feeling this truck has an open rearend. My question is Did GM offer lim. slip in 83' 1/2 tons??? Second of all ,,What size ring gear is in the factory 10-bolts in 83' Is it worth upgrading with a lim slip diff. and maybe gear change??? Or is it something like a 7.5 gm 10-bolts that were pretty anemic. I can't stand an open rearend in a pickup during wintertime. Thanks.