If it is bigger, I'm also going to need different seals for the piston. I don't have a single original spring that survived the OD failure...the biggest part is a single flattened loop, so I can't compare the spring constants (how much force it takes to make it deflect a certain amount).
I took a couple of minutes to figure out what's what with the frictions and steels to make this work. The original 90-95 A4LD OD had three steels at 0.065", three frictions at 0.068", and a 0.200" pressure plate for a total of 0.
599". The 5R55E had two steels at 0.065", two spiral frictions at 0.068" (I'll need your confirmation on this Glacier when you get back from vacation), and a 0.200" pressure plate for a total of 0.
466". For three spiral frictions and four steels I get a total of 0.464", which is pretty close (2 thou under). If we say three spiral frictions and three normal steels and one steel from a 85-89 A4LD OD (at 0.071" thick), we get 0.470" total, which again is pretty close (4 thou over).
I would figure that the drum is manufactured close to the middle of the tolerance range (so that you would use either the .068 or the .082 snap ring to hit the proper clearance), but IF that is true then I could use the thinnest selective snap ring (0.054) and use three of the thicker (0.071" from a 85-89 A4LD) steels and one regular one (0.065") and still only be 0.002" over the other combination (assuming the drum could normally use the .068" one and hit the specificied clearance). I think that is the best idea because the extra thickness of the steel plates add to heat capacity (takes longer to get hot), and add stiffness, which would be the drawback of using a steel plate instead of the normal pressure plate. We are talking about some pretty cheap parts here so I might just get an assortment and see what works.