AT4 68 Dodge 775

Hi all I have just brought my first truck and its a 68 dodge 775 I believe. Just getting it home was a adventure due to the roof nearly peeling off to driving it in the rain with no wipers working the drivers window needed to be jammed with a screw driver to stop it from falling down and only the left side of the trucks lights working. Not to mention sitting on 55mile an hour over 300km trip. I was ready to put it it straight back up for sale when I got home. But a good night sleep and taking the family for a spin in it today and seeing its just a big mechano set, So she's staying and the wife is excited about the project to. This is what I have to the best of my knowledge so far. She's a 68 AT 775 with a 318 5 speed 2 speed diff. I am after info on the drive train, what I need to change to get her to sit on 100kmh without revving her guts out. Just sitting on 55mph she was on 3000-3200rpm and just chewed the fuel. My old man was say they use to interstate freight runs back in the day a sat on 120kmh. I am going to use her as a car transporter for my historic race car. I am starting to go through the threads but if anyone can point me in the right direction it would be great. Cheers!!!

Welcome to the forums.. Sounds like you have a great project, Especially if your wife likes it!!!! There is a lot of help here, just post a few pictures and ask a lot of questions.

Welcome to the forum, I dunno if these ever really did the speeds people claimed, first thing you'll notice is that they wander a bit all over the road, drive it like a yacht, sort of tack from side to side
I dont there are any aftermarket panels yet so that can be interesting
And the speed issue is the same one everyone faces, people chase after 6 speed Commer over drive box

Good luck and ask plenty of questions and take us along on the journey

Paul

it would have had a 361 originally......I have a D2F with a 361 and it would easily do 70 mph towing a bogie trailer...............Just about every bonneted Dodge Ive seen has a two speed Rockwell.......was your diff in high range?.....Edit......3000-3200 revs isnt a lot for a 318,and the gearing sounds about right ..I think the motor is rated around 3600 revs,so it would do well over 65mph......Nope.....318 is rated at 3900 rpm,200hp ...so you were just ticking over ......Anyhoo,if you want thirsty ,then a 361 towing 32 tons gross is close to gallons to the mile,not miles to the gallon.

Sounds like a nice project. Take us along for the ride. I’ve been doing a first time project and tracking my progress along in this forum. There is a lot of help and great advice from the team in here. Pictures are always great. Good luck.

Thanks so much everyone for your replies!!!! I'll keep a running dairy here with the progression of the old girl. I'll get some now pics up and up date as I go. Any advice or CONSTRUCTIVE criticism is welcome!!!! I have already sourced another cab so let the fun begin.

I remember one time I was showing someone how fast a Dodge would go,when a giant wall spider came out from under the dash on the passenger side .....guy opened the door and was going to jump at 70 mph..... screamed like a girl......As I slowed down ,he was hanging out of the cab by his fingers ,and I was trying to swat the spider with a thong and stay on the bitumen.......I knew a couple of guys who used to catch snakes and stick them in a bag under the seat to sell at the pub...good money too....one of them was bit once reaching in under the seat...

Found the diff info. How are the diff ratios interoperated?

The diff is a two speed Rockwell.....there is/should be a electric change motor sticking out the LHS of the carrier ......neither ratio is direct like an Eaton,so it doesnt matter which range you drive in.......The Rockwell is a good bit more difficult to change on the move ,so its probably best to select one ratio before starting off.......or if you are keen ,you can split all the ratios ,like an old timer......Rockwells wont take abuse like an Eaton,and will start to jump out of gear if the clutch teeth get rounded off or chipped.

Is it possible to swap the whole rear axel and diff out with a set up with a taller diff? I can not see me using the low gears in the diff it seems a waste. I'm building her to take my targa race car to events around WA, so no real need for it.