90 chevy 6.0L / Trans

[jamesac91]

I have a 90 model with the 6.0 and auto trans. Can someone tell me what type of transmission would have likely came in this? I believe it is a 3 speed. It is shifting hard and is missing the dipstick, would like to get some parts and filter for it, etc.....Thanks for the help!!

James

[cowlitzcoach]

GM didn't come out with the 6.0L until the 1998 model year in most applications.

In 1990 it would have been a 305 or 350 small block or a 454 big block. The transmission would have been the TH400 or perhaps the TH700R4/4L60.

If it really is a 6.0L it would be the 4L80E or the 6L80 or 6L90. If it is the 8.1L it would be the 4L85E or the 6L80/6L90 or the 8L90.

[Rameses]

Or did you mean to type 6.2?

If that's the case, it's also very likely a TH400.

[DoubleO7]

Originally Posted by cowlitzcoach

GM didn't come out with the 6.0L until the 1998 model year in most applications.

In 1990 it would have been a 305 or 350 small block or a 454 big block. The transmission would have been the TH400 or perhaps the TH700R4/4L60.

If it really is a 6.0L it would be the 4L80E or the 6L80 or 6L90. If it is the 8.1L it would be the 4L85E or the 6L80/6L90 or the 8L90.

You forgot about at least one other big block............
It could be a 366 (6.0L) big block Chevy, used in school buses up to the mid 1990's.

[jamesac91]

Yes, mine is the 6.0L / so all my paperwork is saying. May have to check the motor itself...not sure where to look though. / where on the trans itself would I look to get a better idea?

[DoubleO7]

check via pan shape/config/bolts

Transmission Identification Chart

[cowlitzcoach]

Originally Posted by DoubleO7

You forgot about at least one other big block............
It could be a 366 (6.0L) big block Chevy, used in school buses up to the mid 1990's.

You are correct in the medium duty chassis. But in the P-30 and G-3500/4500 chassis the only big block available was the 454 car and light truck engine. The big block Tonawanda truck engine never made it into the light duty chassis.

[DoubleO7]

Originally Posted by cowlitzcoach

You are correct in the medium duty chassis. But in the P-30 and G-3500/4500 chassis the only big block available was the 454 car and light truck engine. The big block Tonawanda truck engine never made it into the light duty chassis.

I could not tell by his post what Chevy type bus.
Assumed:

[jamesac91]

that is like mine.

[Tootalltechie]

I have a 1974 chevrolet bluebird c60. The engine in it is a 350ci 5.7L. The transmission is a Alison at545. If your bus has a 6.0L 366ci. The transmission is most likely an Alison transmission.

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The Chevrolet medium duty Kodiak truck used the same drive train. Your bus looks to be using gen 1 flip front hood. Hope this helps. Gordon

[Booyah45828]

If you have a full size bus similar to the one shown by Double07 you'll likely have the at545. If its a van built on the one ton chassis it should be the th400.

[cowlitzcoach]

If you have a medium duty chassis you do NOT have a 6.0L engine although it may displace that much.

In the medium duty truck line at the time your bus was built the engine was known as the 366 Tonawanda big block V-8. It has nothing in common with the 6.0L that came out in about model year 2000 in the light duty line.

If you have a medium duty bus with an automatic it will most likely have the Allison AT540 series transmission. It should have four forward gears. Although, unless you really are in tune with your bus, you may not feel every gear change.

[cadillackid]

my original 86 bluebird was like this and had a '454HD' (whatever HD was?) and had an AT545 trans.. on that gasser is was EASY to tell the gear changes, the 545 whistle shifts were more pronounced than they are even in DEV and I hear them in that over the diesel engine.. if its a 545 you'll know it..

-Christopher

[bradmcmullen71]

A 366 chevy tall deck big block is a 6.0 it says so right on the block. Its big brother is the 7.0 427. They are a completely different engine than the newer 6.0 small block. My Allison 545 has very large hydraulic lines compared to the small lines seen on the th350 400 transmissions. If I remember correctly, the Allison has a seperate bell housing from the trans body, the turbo hydomatics are one piece housings. Now that i am thinking about it, not sure if it is a seperate bell housing, but there is an adapter to bolt it up to the gm style block. I would go out and check, but it is cold and dark out there.

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[Booyah45828]

Cowlitz is talking about engine names. As everyone is aware of by now 366 cu.in. roughly equals 6.0 liters. The 366 is a completely different engine then the 6.0 LS based small block that came out in the 90's.

However, in order to avoid confusion when talking about chevrolet engines, most people will refer to the 366 as the 366 and the 6.0 small block as the 6.0 regardless of what kind of tag is affixed to the engine.