I havent seen a aftermarket undertail that didnt require some cutting for it to fit. You could tries Dennis's aka Motorheads undertail kit which totally replaces the stock undercarriage that involves no cutting but you will have to remove the stock undercarriage by removing only four bolts and cutting a slice through the opening hole where the brake oil line runs through to avoid disconnecting it. Once thats done (3min) she'll drop right on out of there.
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Face it bro, your gonna have to get alil dirty if ya wanna lQQk alil funky.