[SCG] When did belt guards appear on 1964 Corvairs?

[William Hubbell]

Do we know the approximate date when the top shroud and idler pulley belt guards were added to the Corvair engine?  Also, do we know if Early Air Conditioned cars used either of these guards?

The guides definitely first appeared sometime in the 1964 model year, as there are two top shroud part numbers listed in the March 1, 1964 Corvair-Chevy-Chevelle parts catalog:

- 3794216 Shroud Assembly, Upper, 62-63 Corvair, FC, 64 Corvair (exc. Turbocharger) (1st design)
- 3851838 Shroud Shroud Assembly, Upper, Corvair, FC (exc. Spyder) (2nd design)

There are likewise two part numbers for 64 Spyder top shroud:

- 3848398 Shroud Assembly, Upper, 64 Corvair, Spyder (1st design)
- 3851840 Shroud Assembly, Upper, 64 Spyder (2nd design)

There is apparently only one listing for 64 FC:

- 3848400 Shroud Assembly, Upper, 64 FC

Additionally, the index listing for "Guide, Blower belt idler pulley" points to section 1.060.  In that section I find the following:
 
- 3851844 Guide, front, 64 Corvair, FC (exc. Air Cond.)
- 3851845 Guide, rear, 64 Corvair, FC

I'm not sure if "guide" is the belt guard.  If so, is the "front" the guide that goes on the upper shroud and "rear" the guide that goes on the idler pulley?

The parts book does not list the dates for "1st design" and "2nd design" - do we have any idea when this change took place?   I already looked in my Clark's reproduction Chevrolet Service Bulletins and did not find anything, but as these are edited reproductions I might be missing the announcement. 

Bill Hubbell