If the differentials are different, that would explain a lot.

Regarding the key, my '96 also has the rectangular switch blade (if that's what it's called) like my VW, but you can't judge it by that. The '96 key system has no programming and replacement keys can easily be purchased "over the counter" without any additional work. Not so with my VW that requires the dealer to program any new key.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL