The following is for OEM seats only, if modified or aftermarket, YMMV.
This is a 2nd gen seat, dimension from bottom to top is ~ 5 1/2".
1st gen seat is ~ 4 1/2".
The bottom of 1st and 2nd gen seats are nearly identical, and have the same part number embossed in them.
~2005 or so and after, the 2nd gen seats were made with a captive (non-removable) post.