according to motodepot.com the progressive springs (progressive pn.11-1128) will cross to the following bikes.  allthough the gs requires a spacer length of 0.75"  as far as I know the stock spacers can be cut to this length so all you will need are the springs.   I crossed a few of the listings into the progressivesuspention.com database and they all came out with the same 11-1128 part number.  allthough they had different spacer lengths.    on a side note the springs were listed on motodepot.com for $59.95 + shipping.


HONDA
VT500 ASCOT (TWIN)   83-84
VT500 SHADOW (TWIN) 83-84

KRAP-A-SOCKIE
VN750 VULCAN           85-02
EX500                        94-96
GPZ500S                    94-96
250 NINJA                   88-97

YAHAMA
1100 VIRAGO              86-99
1000 VIRAGO              84-85
750   VIRAGO              88-97
700   VIRAGO              84-87
XJ700X MAXIM             85-86
FJ600                          84-85
FZ600                         86-88
SRX600                       86
YX600 RADIAN             86-90
RZ500                         85

AFAIK, the springs still sell for $57.95 at Motorcycle Accessory Warehouse (MAW).  See the first post in the Chaparral price hike on Progressive springs!!! thread for links.

Be sure to compare the shipping rates, just in case the cheaper item is actually more expensive as a result.

from what I thought a yamaha radian was the same bike as a seca2 right?      well anyway, the seca2 uses a different spring than the gs acording to the chart.  but the radian uses the same spring as the gs.  someone had metioned that they had gotten radian springs for like 15 bucks on a ebay closeout  so I was thinking about it today,  and you all see the result.....

found these on ebay, shipping is going to be between 10-15$  way over priced as far as I am concerned.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&tc=photo&item=2488972998&category=35592