I've got a pair of knackered old Shimano levers marked only BL-L331. A quick web search suggests the hoods are compatible with old 105 levers*, so the plastic inserts might be as well. They're both scuffed up, but intact. Drop me a PM if you're interested and we can try to figure out if they're any use to you.
* http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0425011195
We have completed some more research with respect to these hoods
(with the help of some recent additions to our Shimano shop manual
library) and are now certain these hoods were made for Shimano's late
80's 105 aero levers (Model BL-1051 or BL-1052...the latter of which
being a short reach lever), as well as Shimano's non-series SLR
(Shimano Linear Response) aero levers of this era (Model BL-L331).
Calmes dans le demi-jour
Que les branches hautes font,
Pénétrons bien notre amour
De ce silence profond.