Westland (212) and Cunliffe-Owen(20). The Seafire F Mk 45 and FR Mk 45 was the next version of the Seafire to be built and the first to use a Griffon 60 series engine with a two-stage, two speed supercharger. The prototype TM379 had been modified from a Spitfire F Mk 21 prototype by Cunliffe-Owen and featured a "sting" arrestor hook. Because this version was considered to be an "interim" type the wing, which was unchanged from that of the Spitfire Mk 21, was non-folding. The fuel capacity of this variant was 120 gal (545 L) distributed in two main forward fuselage tanks: the lower tank carried 48 gal (218 L) while the upper tank carried 36 gal (163 L), plus two fuel tanks built into the leading edges of the wings with capacities of 12.5 (57 L) and 5.5 gal (25 L) respectively. The Seafire F Mk 45 entered service with 778 Squadron in November 1946 and a few were modified to FR Mk 45s in March 1947 by being fitted with two F24 cameras in the rear fuselage. Fifty F Mk 45s were built by the Castle Bromwich factory. The Seafire F Mk 46 and FR Mk 46 was a Spitfire F Mk 22 modified to naval standard and featured the cut down rear fuselage and "teardrop" canopy. Again the wing had not been modified to fold. The electrical equipment was changed from a 12 volt system to 24 volts. The fuel system was modified over that of the Seafire 45 to incorporate an extra 32 gal (145 L) fuel tank in the rear fuselage, while the wings were plumbed to allow for a 22.5 gal (102 L) combat tank to be carried underneath each wing. In addition a 50 gal (227 L) drop tank could be carried under the fuselage. In April 1947, a decision was made to replace the Griffon 61s or 64s driving a five bladed Rotol propeller unit with Griffon 85s or 87s driving two three bladed Rotol contra-rotating propellers. All but the first few incorporated larger tail units from the Spiteful and Seafang. These two changes transformed the handling of the aircraft by eliminating the powerful swing to starboard of previous Griffon engined variants. 200 of the Mk 46s were ordered but only 24 were built, all by Supermarine. The final version of the Seafire was the Seafire F Mk 47 and FR Mk