Re: 8.5 x 10 rear - mono to multi
You can basically do one of two things:
1. Install new multileafs but use the shock anchor plates and shocks from your monoleaf setup. You may find that you need to oval the holes the u-bolts/t-bolts go through (you probably have four t-bolts if your 8.2 is original, but it is best to install at least one u-bolt; the factory performance applications used a u-bolt on the outboard position and t-bolts on the inboard side, but a lot of us use two u-bolts instead for more strength), because the 8.5 holes may be spaced slightly differently. If you reuse the mono anchor plates and shocks, you may find that the shocks do not have enough travel with the new springs (the shocks may be close to full extension with the car just sitting on the springs). Some folks that reuse the mono parts have to add shock extenders (a specialized fastener that adds an inch or more to the top of the shock, fairly inexpensive, $10 or so).
2. Get multileaf anchor plates and multileaf shocks. This is the "right" way to do it, but costs more.
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!