engine identification

how can i identify if my 95 4.6 hse have a 46d high copression or 48d low compression engine number?according to the VIN it's fabricated in the uk.i wana know if i put 98 octane or 95 octane fuel.did a search and tried 2 locate the num near dipstick but no succes.searched in google and found 2 results;
1. 46d 1994 onwards high compression
2. 48d 1994 onwards low compression
Thanks

The number is right next to where the dipstick shaft goes into the block. It will be to the front side of the dipstick tube on the flat bit of block that the tube goes into.