Sorry if this is a repost because I know that I have seen other links to Howstuffworks.com on this site.
Here is a link to a page on Howstuffworks.com that appears to be a patent for a Chrysler transmission. From the date that is on the patent application and the description of the transmission it seems that the patent could be for the 42LE. I have not read or even skimmed the whole document but it seems like it might provide some interesting information on Chrysler transmissions, if not the 42LE.
To apply the underdrive clutch assembly 308, hydraulic pressure from fluid entering between the input clutch retainer 326 and second hydraulic piston 410 moves the second hydraulic piston 410 axially, thereby compressing the spring 432. The second hydraulic piston 410 forces the rotating clutch plates 342 and momentarily stationary discs 344 of the underdrive clutch assembly 302 together and produces frictional force between the clutch plates 342 and discs 344. Because the input clutch retainer 326 and underdrive clutch plates 342 are rotating, the frictional force causes the underdrive clutch discs 344 and hub 350 to rotate, in turn, rotating gear shaft 352 of the gear assembly 500. When the hydraulic fluid to the underdrive clutch assembly 302 is vented, the compressed spring 432 applies a force to the second hydraulic piston 410, thereby returning the second hydraulic piston 410 to its non-applied position as shown in the figure.