Some have side connectors on top, but that is a really odd duck. If it is a bottom connector, more common, that can be either a 2 or 4 pin connector, with two possible options for positive/negative, You can check your battery to see what you need, and buy the same type. Nonetheless, when you get the new silverfish, verify that it was delivered with the right polarity as advertised.
Most have the same dimensions at the bottom, around 75x110, but check to see if yours is comparable. Finally, the height varies. They use taller cases for the really high AH packs. Compare it to your pack. These usually ship with the rear metal bracket, which contains the hole for the keylock so you can use a taller pack.. You can put a second hole in that bracket to accomodate a shorter battery, If you buy a taller one, make sure it doesn't interfere with your seat.