I have seen early Novas with brake master cylinders that had a screw down cap on them. My 65 has a delco with a clip on cap and I believe it was the original. A guy on ebay is listing one that is the screw down cap as an original for 65. Were both of these available in 65? Was this an early/late thing? Did all the 62-64's use the screw down cap master cylinder or did they use both for several years. One picture in the 65 assembly manual shows the clip on cap and another shows the screw down cap. In either case there doesn't seem to be an exact replacement availabel for these.