Also see: Production Twin Cams and Notable MGA Deluxe

Early Predecessors to the Twin Cams:
EX-172 - 1952 not an MGA, but a rebodied MG TD built to run at La Mans.
EX-175 - 1952 First factory prototype for MGA, based on 1952 EX-172 Le Mans car. More information.
EX-175 - 1954 (2nd car) still with MGA body style, Bonneville speed record 153 mph - Also averaged 120.74 mph for 12 hrs. Combined an MGA chassis with an unsupercharged modified 1500cc TF engine. More information.
EX-179 - 1956 EX-175 from 1954 rebodied as streamliner, now Twin Cam 1500 engine. Bonneville speed record 170 mph. At one time held almost 100 International and World speed records. More information.
EX-181 - Streamliner. 23 Aug 57 - 1489cc Stirling Moss 245.64mph (395.31 km/h).
EX-181 - Streamliner. 3 Oct 59 - 1506cc. Phil Hill 254.91 mph (410.23 km/h), to this day still the fastest ever MG. More information.
EX-182 - 1955 - Four built for Le Mans, three raced while the other was a practice car. Redesign from EX-175 with new B-series engine. One competed in Dundrod Tourist Trophy race 1955 with Morris designed Twin Cam 1500 engine, which was eventually used for the production model with 1600cc displacment. More information.

Prototype Twin Cams:
ND?/13/498 - - 1958 Twin Cam Prototype - More information
NDL/13/500 - ORX885 - 1958 Twin Cam Prototype. - More information

Special Production Twin Cams (Works Cars):
EX-182/41 - 1958 reincarnation of the 1955 Le Mans race car EX series, this time built with a new twin cam chassis and aluminium body. The chassis number is not known (at this time), so it is hard to say if this is a pre-production or early production Twin Cam works car. - More information
EX-186 - 1958 reincarnation of EX-182, Twin Cam engine, never saw competition. - More information
SRX210 - Modified body MGA Coupe, Twin Cam, Le Mans 1959-1961 - Probably built using an EX-182 aluminum body shell. - More information

Also see: Production Twin Cams and Notable MGA Deluxe