hmm, odd indeed, to your question, I've been looking at the manual that came in the box.
Seriously tho, yeah on page 18, listed under the options assemply diagrams.
It clearly states, OP499, 53499 Wheel Axles for Assembly Universal
Shaft set. Also states it's to be used with OP500 and OP836. Diagram
even shows how to assemble them.
In fact, I'd say it's the identical page comes with the stock TA05 Manual.
I'd scan and post it for ya, but I don't feel the need too.
I've already contacted Tamiya Canada, but I'm not sure of their turn around time in regards to communication with them.
The product ID the manual has is RCC TA05-IFS Chassis (11050632). It looks to have been drafted on 0607 based on the copyright.
Very odd indeed,