Rancho and BDS probably make springs. Check Hoak's for BDS.
Weak link would probably be the axles, especially when you start lifting and going to larger tires. The rear should be a full floating D25. Definitely carry a spare axle shaft or two. The front is also a D25. Check what joints are inside. The close knuckle D25 can have one of three types of joints. 2 are CV joints and have a tendency to wear until, at a bad moment, the balls will lock between the shafts and housing and grenade. Later on, they changed to regular universal joints. Bensinger might have a set of these out of a later Jeep and trade you for the originals. The u-joint versions are repairable and less likely to destroy everything just due to wear. Depending on the life of the MB, the T-84? transmission and transfer case could be fairly worn. The transmission uses bushings for the countershaft versus the needle bearing in the CJ T-90's. The transfer case is an early Spicer 18 with a 1.89 low range and a 7/8" intermediate shaft (the smallest design). While this will hold up to moderate wheeling, if you start building it up, you may want to upgrade to the T-90 and get a D18 out of a 50's+ CJ which would have the 1.125" - 1.25" intermediate shaft. If you decide to just swap the axles for later ones, most of the 4 cyl Cj's had 5.38 gears versus the 4.88 gears in the MB.
This is just what comes to mind from the stories I've heard over the years. The MB will serve you well stock, but if you add grippy tires (which isn't tough compared to the military tires), or larger tires you might overload the stock components. In fact, I've heard of rear axle shaft failures in stock vehicles that may not have been doing what's up at RC.
- Dave