need help with charging/starting problem

[Rdub]

Okay, I've been hanging out here for around a year & need some help.... I have a 71 GMC K10 which I puchased about a year ago. I have receipts from local shops for an engine rebuild and RV cam instal about 25K ago and overhaul of transfer case and drivelines about 15K ago. I don't plan (yeah right ) to make any chages except electronic ignition this next spring or summer.

Okay, here's the problem... shortly after I bought the truck I started having problems with low/dead battery. Figured the battery was shot and wouldn't hold a charge so put in a new one this last summer. BTW, I do pretty good with AC wiring, remodeling around the house etc., but am lost when it comes to automotive wiring/electrical stuff..... anyway, new battery was good for several weeks then finally the problem started reoccuring. I don't drive it often, maybe once a week and probably don't average 100 miles per month to Home Depot etc. Lately I've been disconnecting the negative bat. terminal when I'm done driving and that seems to work okay.... so I drove the truck last weekend and disconnectred the neg. terminal. Wanted to pick up some stuff after work today for a home project so decided to drive it today. Went out this morning connected the batt. & noticed it didn't crank very well....drove it about 1/2 hour in stop & go traffic, & parked at work.... went out about 5 minutes later to move it and the engine turned over about 1 time and now I need a jump....... question is can you guys give me some obvious things, maybe a prioritized list of things to look for, replace or where do I start?