Always good to have a ground on a Bell Housing bolt too. For the life of me, I am trying to remember what the deal was, but there is something about not having enough grounds to motor and trans, and ground was arcing to the front pump or the front seal of transmissions and causing lock up failures in converters, or burning front pump seals or some crap like that. At any rate, it was causing a biggo trans failure of some sort, and the issue turned out to be lack of grounds. Point is, just the Negative Battery Terminal to the Alternator bracket isn't enough. I'd probably go with another from the firewall to the motor since the cab is also bolted to the frame on rubber bushings, and another from the block to the frame. This way you have all your basis covered. Block to sheetmetal, Block to Iron frame, and Block to Battery, you should be good to go.
Then, things like your instrument cluster are plastic, so you'd need to take ground to sheetmetal etc. This is what we mean, you can't have enough grounds. If it doesn't ground naturally, then add a ground to it in the proper place. Taillights for example. Also plastic, each must be grounded to the sheetmetal or they don't work. An idea of a natural ground, would be the starter. It bolts direct to the block so it's naturally grounded, (provided you have the block grounded to all basis).
