Actually I made the local IDI(BOOB) meet this past summer. I made a one day appearance and hung out for the day. Had a great time. No real time for driving lessons though
. I've been a member of FOKISD for a number of years now, but sold my PSD back in '02. I'm still "allowed" to hang out with the guys as long as I bring one of my hot rod toys
My truck has a Triplex(15 spd) box in it. There were Duplex's(10 spd), tri's and Quads(20). The only difference is the number of "compound" gears you can split with. The only advantage of the Quad was a lo/lo gear for really creeping around. There were also variations of all, with either single or double overdrive which then also made some gears repetitive and not usable. So you have 20 gears, but only 18 usable gears since a couple were the same. See what I mean? With this you have 3 reverse gears too.
Some of the newer (well like in the 80's)Mack tranny's had air shift Rev so you have 5-6 reverse gears(shift to Rev and use all the forward gears).
It's fun to play with, and I usually skip along the gears when bobtailing. As Fred said...LOW power, narrow powerband keeps you moving the handles around if you're loaded. My truck/trailer combo is around 27K lbs, so I'm not real heavy, but with only 170 hp...it's a bit slow sometimes. It will run 63~ mph on level roads.
My tranny is pretty loose. I put a few gallons of Lucas in it to help "tighten" it up a bit. It rattles and grinds pretty bad in neutral after a long 8 hr drive(heck 1 hr for that matter). Some day I'll do something to help it....