World class uses ATF.

Non-WC uses gear oil.

You need to find out what you

 

Its in the car and its my only driver. How can I find out? Will ATF really hurt it? I dont drive it super hard.

 

If it's a V8 box and it has a 2.95 1st gear, it's a non world class. 3.35 is a world class box. This is assuming it's from a production line car and not from a GT40 Mustang which not too many were made.

I don't think AFT would hurt a non world class box. They use to run AFT years ago in 4 speed cars to make them shift faster due to less parasiting drag. Check to see if you still have the trans tags to find out what you really have. I think actually they don't use AFT but a "MT" lube that's thin like AFT.

 

Where do you get this from?? Or are you referring to transmissions that came IN cars?
Just about all WC T-5's are 2:95 first gear transmissions.
Just go check out the World Class FRPP M-7003-Z trans at Summit Racing. I've got the same one going in my '66.

Ford Racing M-7003-Z - Ford Racing Super-Duty T-5 Transmissions - Overview - SummitRacing.com
In the foot notes:
Features:
* Heavy-duty "World Class" T-5 5-speed manual transmission with short-throw shifter.

 

It has no tags on it. I got it from a wrecking year. Im pretty sure its not a world class but then again it could be.. well if you were me and couldnt pull it out at this point in time and see what it really is what would you put in it? Thanks for your help.

 

I think if you've been running AFT this long with no problems...why change? The only way of telling a world class by looking at it is this. The front cluster bearing cup (bell housing side) is recessed a little bit. The non world class is flush all the way across the cup.

 

I hear ya! Just drive it til something goes out if anything even does. Thanks tho cause its been kinda bugging me, i little piece of mind. In your opinion what would be the best transmission to put in a 65 mustang with a 289 pushing 350 hp? Im not a huge fan of the t-5.

 

I put a WR Toploader in mine. IMO, forget about dyno hp. On the street you're only going to make as much hp as you have traction. If your tires break loose at 150 hp, that's all you're going to make basically and your T5 will be fine. I once read on another forum where a guy had a 408W in a Cobra kit car using a 4 cyl T5 and never had any issues with the T5 even after many smoky burn outs because he said he didn't have traction. He also went on to say if he did have tration...it would be a different story.

 

Tko500

 

On the driver side of the T5, above the backup light is a bolt. If it is a Torx bit it is a World Class. If it's a hex bolt, then you've got an older non world class unit. Here is the location highlighted in a red box

More info I put together on How to ID a T5: How to ID a T5

 

My T-Bird Turbo Coupe (4-cyl) had a T-5 and ATF was the recommended fluid.

 

OK, I see what you are saying now. I bought mine probably 10 years ago and has been in the shop ever since. But I do remember getting to choose my 1st gear ratio when I purchased it from D&D Performance. I went with the 2:95 since I installed 4:11's in the rear.

 

Manufacturer, Tremec, specifies GM Synchromesh Lube. As close as your nearest GM dealer.

Don

 

I use Royal Purple Synchromax in my Tremec 3550. You can get it from Napa and it's around the same price as the GM Synchromesh. The last time I bought it they were close to $10 a quart.