Why do I keep having to replace my starter?

[Chevy4x4chick]

My truck is an '84 Chevy K30 4x4 with an 8.1. I bought it 2 years ago, with that engine in it, so don't know anything about the swap. Part of me wishes I would've bought one with a good ol' stock 350 in it, but it's a blast to drive...when it's not dead in my driveway. My starter is toast for the 3rd time in 2 years, and this truck is not a daily driver. The second one I installed myself by watching a YouTube video (yes I'm a girl lol). So, I thought maybe I did something wrong. The third one I had a friend who's been working on Chevy trucks for over 30 years install. So before I go fork over money for yet another starter, I need to figure out what is causing this. The truck is very cold starting, definitely not a fire it up and go type. Ideas, hints, comments?