Not in the UK
this is what I found on another forum.
The W140 S 280 was introduced in Germany and most world markets at the early stages of the facelifted model. Hence, there was no W140 280SE with the original pre-facelift design. The S 280 originated in an attempt to broaden the W140 public appeal and to offer a more affordable model. The W140 S 280 had some very peculiar features:
1/- As it happened with the earlier 260SE (W126), the W140 S280 was woefully underpowered for its bulk and size.
2/- It was available only in short wheelbase form.
3/- It was equipped as standard with a FIVE-SPEED MANUAL TRANSMISSION. It helped the underpowered pick-up of the 2.8 liter engine and made the car more affordable.
4/- In Germany, and also in most markets, it also came equipped standard with cloth upholstered/manually operated seats, without any A/C and tintless windows allround.
5/- It sold in very small numbers. Production figures are insignificant compared to the S320/S500 which were the best sellers of the lineup.
I dont think a manual s280 was ever marketed in the UK.
Reputedly it was as a passenger in a s280 that Princess Diana was killed in Paris rather than the often reported s500? Something to do with the French road taxation rules for cars over 3000 cc.
thanks to A Rosich from Costa Rica for that INFO.
edit you could try this german company
http://www.speed-autoteile.com/
they certainly list s280 parts in their online catalogue but not your part I'M AFRAID. try e-mailing them direct.
OOPS if its missing you cant. you can tell I,m just in from the pub! 
try the online parts catalogue and compare part nos for 5speed w210 and w124 with w140 see 
