Yeah it should be 34mm in 1985 just like the 15th Anniversary models from 1984.
My '84 Trans Am WS6 has the 32mm.

 

I own an '85 T/A that I think is a WS6 car. On the dash, there is a small badge that reads "Performance Suspension". It has a 34mm front sway bar and rear drum brakes. I have always questioned whether this was a true WS6 car because of the drum brakes. It also has the 15" aluminum wheels which I'm not sure are correct. 1985 was that year when the interior got redesigned but the underpinnings were still 1984 for the most part. A previous post mentioned the rpm when going a certain speed. My car does about 2200rpm at 75mph. I think the axle ratios for 1985 were 3.08 or 3.23 for the automatic; so what do I have? It's an LG4 engine with cruise, airconditioning, tilt wheel, and manual mirrors. As someone else mentioned, it doesn't matter to me if it is a true WS6 car, I still love it just the same.
After further research here on the board, I think I may have the F41 suspension package. That would explain the bigger sway bars, drum brakes, and 15" wheels. Or do all Trans Ams have the badge on the passenger side dash that says "Performance Suspension"?

 

From 1982-1986 WS6 included rear disc brakes, never found a deviation from that. I suspect you have the F41 Suspension, as starting in 1985, the Trans Am with WS6 should have the 16" Flat (often called Formula) Rims. Starting in 1987 however WS6 was only the suspension, and the rear disc brakes were a separate option... With that said rear discs were mandatory with the L98 and the LB9/M5 cars with the performance gear for sure. However some years (91) the rear discs were not available due to shortages of parts, and they got the Aluminum rear drum brakes.