I know this is an old thread (and the forum warned me also), but I think it's still a "current" issue - at least - it's a problem that I've just experienced, and here's how I dealt with it.
It seems that Suzuki does not supply what they call the "#1 lever boot" - the one that seals directly to the transmission or transfer case - as a separate item, but requires the entire shift lever to be replaced.
If all you need is the rubber boot - you can use the end section of a steering rack boot - choose a steering rack boot where the narrow portion of the accordion pleats will fit the neck of the transmission or transfer case housing and with a tie-rod end close to your shift lever diameter and cut the boot to the length you need.
Use a little bit of dish washing liquid on the tie-rod end of the boot to lubricate it and gently ease it down over the tapered portion of the shift lever, fit the accordion pleat over the transmission or transfer case housing neck and secure it with a nylon ty-wrap and you're good to go.