Should be a 10 1/2" 23 spline like mine. Check Rockauto for the size. Mine's a 70 318 in mine but it had the 10 1/2".
http://www.rockauto.com/catalog/raframecatalog.php1967 PLYMOUTH BARRACUDA 4.5L 273cid V8 : Clutch : Clutch Kit Price Core Total
RHINO PAC Part # 05029A
Base; Diaphragm Option Kit; Disc Spec: 10-1/2" OD X 1" ID X 23T, Flywheel Spec: Flat
$138.79 $0.00 $138.79
$139.79 $0.00 $139.79
RHINO PAC Part # 05029
Base; Disc Spec: 10-1/2" OD X 1" ID X 23T, Flywheel Spec: Flat; Lever Style; Standard Kit
$142.79 $0.00 $142.79
SACHS Part # K167503
10 1/2 Inch Clutch; OD: 10 1/2; Size ID: 1; TEETH: 23T
* Non-stock item--shipping delayed up to 2 business days
$130.79 $0.00 $130.79
