It's not too difficult to replace, you can see it when you remove the air cleaner box.
The 1998 has a slightly better tranny, but the same PNP. I am a firm believer in using the shift lever to down shift in the local 30mph zones. The 1998 ,with the S and E buttons, keeps the tranny in 2nd while in Low unless you come to a full stop. This also keeps the engine rpms up, which helps lubricate parts instead of lugging along at 1200 or less rpm. At the same time, the PNP switch gets more use and stays cleaner.
Bay13 has a good write up on PNP replacement.

Klaus
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1975 164E running? 1995 854T sweet 1998 V70 R work horse