I think they package the same diagonal with the Meade Adventure 80 which is a ST80,I could be mistaken?,never even tried mine, just threw it into the box and use a low cost prism diagonal that works just fine,D
The housing is somewhat differently shaped and the nosepieces are somewhat different. However, they use much of the same internal form, differing in the internal screw pattern for holding it together. The prisms appear to be the same (without actually removing them.) They both have what appears to be the same small aperture angular piece covering the prism just below the eyepiece holder.
I haven't measured the actual apertures of these two RACI's, but they appear to be somewhat less than that of the #PD90 GSO RACI (which is identical to a much older RACI that came with an 80mm finder.) The prisms are likely the same size, but the larger GSO aperture is all the way to the angular edge of the prism. The GSO RACI has a metal eyepiece holder and weighs 1.3 oz more (3.5 oz vs. 2.2 for the Celestron.)