if you are climbing mountains Overdrive is a huge advantage.. or well I shiould say more gears is an advantage..
a 5 speed stick and a tall rear gives you the sane effect as a 5 speed auto with OD an d a shorter rear..
4 gears is not a lot for climbing and descending mountains in a full size bus.. lockup or not..
can it be dione? of course it can.. but often you figure that your last gear in whatever trans you have is your main highway gear... the only time you really use it is at speeds 50 and higher.. (at least for as bus you want to travel comfortably 65)..
get in the hills and that gear is useless.. so now you just have a 3 speed.. on the steep hills you may find yourself dropping to 2nd or wishing you had a gear between..
so enter in an OD transmission.. a 6 speed.. (MD3060?) so you have your 6th for the main highway gear.. 5th is for small inclines on highway, and 4,3,2 can give you a nice selection as you ascend and descend... theres your "in between" gears you wish you had..
more unusual solutions are 2 speed rear ends or divorced aux transmissions. that give you multiple ranges to travel at.
obviously gears are also a stop-gao often used when running less-than-adequete engines in situations where you should have more power..
the ultimate engine would probably be one that had enough HP to just run up the side of a mountain in any gear you want... but those get pricey...
when I drove that $750k coach back N forth from florida to ohio for those friends of mine each year.. its 450HP motor rarely dropped out of top gear on the big hills...
-Christopher
Based on what I have read/heard, a good 8.3 and 3060 should easily last 300,000 miles without problems if well maintained, cruising at interstate speeds. Most mechanics I talked to thought that a 6bt might start to show its age at around 150,000 miles. I would still love to find someone who would be willing to put a 6bt into a Chevy suburban for me...that would be a really sweet, durable deal also.
