late 1990 went to the oval type speakers same size as the original front door pockets were. before that they were round type fitted to a metal surround plate that mounted to the body on the later cabs the rear card was flat and housed the speaker in the doorcard itself allowing a bigger speaker. the older rear cards were a moulded type which makes it more difficult to mount an external speaker.
You can mount oval type speakers shifted at an angle to sit behind the original housing if you have the old type of rear card. I changed the rear cards and copied the later flat ones in foamex and retrimmed to match, the font ones were retrimmed to the later door design to house the larger speakers they are a straight swop with JBL component speakers, the tweeters that come with that set fit into the standard surrounds and have a slightly larger diameter cone than other makes of mids the crossovers for these sit behind the doorcard underneath the front quarter window, a small sub with enclosed amp to increase boot space as it has to carry shopping sits in the back, one more amp powers the rest that is hidden behind a retrimmed boot card.
