Dave,
These parts were created to either repair a broken Scalextric chassis that broke at the pick-up guide and/or to replace the standard Scalextric guide blade with a Slot-it guide blade. The Slot-it guide blades are more robust than the Scalextric guide blades.
The B-NOVA Guide Adaptors do not a part number as such and come in packs of three different sizes (1/32, 1/16, and 3/32 thick) so you can get your guide at the correct height for the car you are fitting the Slot-it guide blade to. Slot-it guide blade part numbers are CH10 for plastic tracks ($4.99) or CH7 for wood tracks ($5.99). Also, you would then need a few brass eylets and guide braids.
Hope all this information is of use to you but you will find the Slot-it guides to be stronger and the cars handle better than with the Scalextric guides.
Cheers,
Henning