I have seen the opposite done, so I'm sure it is "possible." In broad terms, you would need at least the transmission and associated computer, new shifter hardware and a new pedal assembly. You can probably review the online catalog at delorean.com to total the cost of parts new. Someone told me they thought it would cost them about $5K in parts alone to convert their automatic to a five-speed. I know someone with an automatic tranny and engine sitting in his garage. I think he only wants $3K for the whole thing, including the turbo, but everything needs work. As with all things cars, it probably comes down to how good you and your tools are... labor will really drive the cost up. Assuming you already own a DeLorean, even though I know it's easy to get attached to your particular car, you might consider cleaning up your five-speed, selling it, and buying a clean automatic. Given that the five-speeds are a little peppier, they probably command a higher price. Cost? Zero. You might even pocket some money.