What are the real differences between the ATE and Girling setups? I have whats labeled as a Lucas booster and master cylinder which is, from looking at pictures, the same as a Girling. Weren't these found on later cars? Are the master cylinders interchangeable between the boosters? What is the weight difference between a steel and aluminum unit? Also seems like there is a difference between the early (PP-477.611.303B) and late (PP-951.355.303.02) reservoirs.

In case some aren't on the NASA forums, I need to change my master cylinder. Loosing pressure and I have a leak where the booster and master join. I want to make sure that I get the correct one for my booster if it does make a difference.

Ive found a parts place that has a steel master that is advertised as being compatible with both booster but don't know if there would be a disadvantage to running a steel over aluminum unit.

The late cars only came with the aluminum Ate boosters (951. part #). The real difference is the fact that aluminum boosters don't rust. Now, this is unlikely to be an issue for your race car. I don't know the answer to the weight difference, but I do know that they are interchangeable. Maybe one of the parts places can give you the shipping weight of each part before you buy one?? I would think that they are pretty close, but every little bit counts!

We swapped my brother's '87 944 street car's aluminum Ate with the steel Girling, simply because of the difference on cost.

Hope this helps!