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85 GMC with a 427 Help Jimmy 9-1-05  
I am looking at a 1985 GMC school bus with a 427 motor the person who is selling it don't know what kind of trans is in it, they said that they drove it 65mph down the Hwy..any help...on the motor and Trans and how about gas mileage since it is getting to $2.75 a gal....I will we using it for a party bus to take to the lake here in Austin Tx they took all the seats out and it is 38ft and 28ft from the driver seat to the back and I think it has low miles on it
Re: 85 GMC with a 427 Help Phil Feinstein 9-7-05  
I found the post you are referring to; The Allison 545 is a great tranny from what I've heard, but it's not used on gas busses from what I've seen. It's used for busses with Diesel engines.
Re: 85 GMC with a 427 Help Phil Feinstein 9-6-05  
This bus is new enough that the trans type can be derived from the VIN number. If you can get the VIN, you can find out just about everything you want to know about it.
Re: 85 GMC with a 427 Help Phil Feinstein 9-2-05  
With a 427, you're probably looking at the Turbo 400 or some varient of Powerglide (727, etc.). You can figure this out by looking at the metal tag attached to the pan or tailhousing on the trans.

Gas mileage depends on load, tune, speed and how heavy your foot is. If you carry light to moderate loads, keep the motor tuned and keep your foot off the pedal as much as possible, the best you will see is about 10 to 12 MPG. Keep in mind that you are looking at a big-block V8 and that it will use gas respectively. If you luck out and it has a TBI fuel system, you may see 10-12 MPG regularly. A carb makes that number harder to come by.

Hope that helps!
Re: 85 GMC with a 427 Help jimmy 9-7-05  
Thanks Phil, I'm not sure if this deal will work out.But doing some reading on this site and others that if I did buy a bus it will have a DT466? auto,with air supension & brakes and under storeage, not sure on flat face bus because I want to put a deck on top and on the back with a rear door and I would like a taller inside also 6.5ft,MAN I'm asking alot for little money in pocket Thanks Jimmy, Austin Tx
Re: 85 GMC with a 427 Help Jimmy 9-2-05  
Thanks Phil for the reply back, I don't think it is a powerglide, they quit making them before this was build, I have them in my 64 impala ss, and the 727 is mopar,what about a 645 ? which I think you had mention in a older post if you are going to get a bus get this Tranny...the owner lives 80 miles a way and will be moving 200 miles away from were the bus is stored so he don't know much about it.
Re: 85 GMC with a 427 Help Phil Feinstein 9-8-05  
The DT466 is also an Alison tranny for Diesels.

You know what you want, so you may want to try I'm sure my friend Mario at the Kankakee, Il location can hook you up. I'm very happy with the van I got from these guys, so I can vouch for them being a good place to buy from.

To see what a Crown bus looks like with a raised roof, go to and follow the links for the 1964 crown in the "Bus Barn" section.

6ft is the standard height of the inside of a school bus; 7ft is the standard height of the inside of a transit or coach bus. You might want to look into a flat nose school bus for 3 out of 4 of your wants, but if you go with a school bus you probably won't get the interior height you want.
Re: 85 GMC with a 427 Help Jimmy 9-29-05  
Thanks for all the help, I havn't decided what to get, and this deal looks like it will not work out. I will kept looking and in no hurry, we have alot of hills here in Austin and I will be needing to climb these hills and when going to Houston or out west where it is flat ( I -10) to go Hwy speeds, I guess I want the best of both worlds.
Re: 85 GMC with a 427 Help Rick Wells 10-14-05  
I have a 1976 Blue Bird with a 427 AND a 545 allison. it does 60 mph and gets around 7 or 8 mpg. You can get parts for this engine at any auto parts store because they put this engine in big chevy trucks for 30 years and any shade tree mechanic can work on it. You can pay at the gas pumps (mpg) or pay at the shop (diesel mechanic, 3 or 4 batteries, $400 dollar starts etc) but either way you can't drive one cheaply. Rj
Re: 85 GMC with a 427 Help Scott 9-27-05  
I have an 83' GMC Bluebird with a 427. I replaced the 366 original motor. Mine is a 5 speed and I only top out at 53MPH without over-revving the engine. A lot has to do with the rear end gear. Mine is 6.-something. Find out if the owner had it replaced by a 4.11. That gets you about 70 MPH. I used to run the 366 at about 70 until I blew the piston right out of the side of the motor. My bus is full sized and gets 9-10 MPG with the current setup.
Re: 85 GMC with a 427 Help ron 9-13-05  
If its got a 427 it is rare all the chevy buses i have drove has the 6.0 366 they look like a 427
Re: 85 GMC with a 427 Help Phil Feinstein 9-8-05  
Wow...My bad entirely

The DT466 is an engine, not a tranny!!

466 cubic inch Detroit Diesel

DT360 and DT466 are common diesel engines. There's also an 8.2L diesel, which would be a DT500.
Re: 85 GMC with a 427 Help Rickster 11-25-05  
Lot of confusion here I'll add some more
The Allison 540 series of which the 545 is one can be found on gas engines by GM,Internationaland maybe Ford. The 600 series are better but not that common on school busses.
The DT466 is an International(navistar)six cylinder diesel related to the DT360. International also made the 7.3(444) and 6.9(420) The 8.2(500) is a four cycle Detroit Diesel. The 427 BB Chevy was an optional engine and as stated is very similar in size to the 366 BB.
If interior hieght is a concern check out some of the "high roof" Thomas school busses.
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