Long shot. Engine ID Chart shows QR, QS and QT were used that year.

 

As well as QW, QL & QU for the 400cid engine.

QR: automatic, 4 barrel, high compression
QS: automatic, 4 barrel, high compression, air conditioning
QW: manual, 4 barrel, high compression
QL: automatic, 2 barrel, low compression, air conditioning
QT: W30, automatic, 4 barrel, high compression
QU: W30, manual, 4 barrel, high compression

Manual section 6-1, page 100 of the '68 assembly manual.

Randy C.

 

Good to know!
i saw those on my chart but not sure if they would fit.