either a turbo 350 or a 700r4 (added to answer) the only trans available was the 700 R4 in 1987. 81 was the last year for the 350 and at that is was electronic lockup. 1979 was the last year for the...
depends on engine if 305 you can fit a 200r4 or 700r4(recommended) 350 will fit the 4L60E most of tha caprices with the 350 are electronicly shifted...
You didn't mention the year of the caprice so I'll try to cover a couple scenarios that will depend on whether it originally had a turbo 350, a metric 200, or a 700R4. First, understand that Turbo...