I just recently pulled my engine and transmission out of my 72 nova,and the transmission is a 350 turbo but on casing it has a big "L" stamped in it . Does anyone know what kind of tranny this is?????  

I think that is just some sort of manufacturer/plant/date code.  It should just be a standard th-350.  I am pretty sure mine had the same thing on it but I ain't pullin' it to look.  

Casting marks and stampings are meaninless,  the way to tell is to look at the pan shape.  350 are basicly square with one corner cut off.  it would be either a 350th or a 400.  There are dozens of wbsite with tranny pan shapes for ID.  Matco sells parts and has a good id chart on there site.  

Except for some diesels Chevrolet didn't use "L" code T350s.  A stamped or placarded "L" is usually part of a calibration code, at a minumum this should have two letters like "L A" or "L K" or "A L".

T350s and T250s are built by Chevrolet and Buick for BOP divisions. Under any circumstance there should be a VIN code code stamped into the transmission. For Chevy built, its located on the right side toward upper front where the transmission case blends into the bellhousing. This can't be read without a mirror when the tranny is installed. For BOP the code is stamped on the left side by the shift arm. If the tranny is original to the chassis, its VIN will match the vehicles.

There is a model code that on Chevy built transmissions will be stamped on the right side of the oil pan. For BOP it will be either on the accumulator or governor cover. Turbo 250s also have this code on the governor cover. I sight the T-250 as unless you look at a lot of GM turbo hydramatic transmissions the visual ques between the T-350 and T-250 are slight.

The calibration code where the "L" would typically be found is usually part of a two letter code ink stamped or stickered on the bellhousing. Another thing to look for is the engineering code which will be letters cast on the bellhousing. For Chevy 350s it will be "MV4".  M33, M39, MX2, MX3, MX5 would be a BOP unit. M31 or M38 would designate a T-250.

T-250s show behind 6's and small V8s but it's not unhead of to find them behind a 350. Chevy built transmissions are found only on Chevy engines because of the bolt pattern. Buick built BOP units can have BOP only bolt patterns or a combined BOP and Chevy pattern, therefore, they can be found on anything including Olds engined Caddys.

Confused yet?

Bogie