The MGA Twin Cam steering rack is set a little farther forward to clear the crank pulley on the longer Twin Cam engine. This trait was also carried over to the "Deluxe" cars after end of Twin Cam production. The Twin Cam steering rack also has a longer input pinion shaft to locate the universal joint in same position as the standard cars (not to change the steering column length). The Twin Cam steering rack also has the Zerk fittings on the bottom side for easier access.

Now for a bit of concours trivia. On 11/17/2020, Mark Wellard in Australia wrote:
"I noticed a dab of yellow paint on the underside of my steering rack housing. (Picture above). This is probably to differentiate the Twin Cam racks from pushrod racks at the factory, as they did with the gearboxes".

Addendum September 26, 2021:
A picture showing the approimate 1-inch difference in length of the steering rack pininon shaft. Photo compliment s of Ian Renshaw.

Notice the angled gear teeth on the pinion shaft. Gear teeth on the transverse moving steering rack are straight teeth cut perpendicular to the rack motion axis. The inout pinion shaft is positioned at an angle, not perpendicular to the rack. Therefore the gear teeth on the pinion shaft must be inversely angled to cancel ouit the shaft angle so the gear teeth mate perpendicular to the rack axis. Difference between Right Hand Drive and Left Hand Drive steeriung rack will have the pinion gear teeth angled in opposite direction.

On 1/1/2024, Mark Wellard wrote:
"I've had trouble with oil dripping from the steering rack nipples of both of my cars. I tried new grease nipples to no avail, with the racks relieving themselves of oil over a relatively short period. I hadn't been able to find a solution but yesterday I tried a squirt from a grease gun, hoping that the grease would plug the leak. Success! No leaking at all in the past 24 hours. -- Mark

Adrian Gregory via groups.io wrote:
"I have the same problem. Smelly EP oil on the cardboard sheet under the car. I tried new nipples too to no avail. I am looking forward to trying your suggestion! -- Adrian

Simon Crispe via groups.io wrote:
"My understanding is that conventional grease is not such a great lube for steering boxes and racks because it can displace away from the contact surfaces and cause excessive wearing of the precious metal! -- I've always used Penrite fluid grease per the attached which is readily available in NZ and no doubt most other countries as well? It has the advantage of remaining relatively fluid and can take the quite high pressures generated in the steering gear, but is nowhere near as prone to leakage as gear oil". -- Simon

https://www.britishautousa.com/products/penrite-steering-box-lube-500ml

John Russellin in Devon, UK wrote:
"I have replaced the oil in my racks with Land Rover Swivel Housing Grease (you can find it on Ebay under this description). It was designed by Land Rover to reduce the oil leaks from their front wheel swivel hubs, which were previously oil-filled. It is best described as a 'non-runny oil' that will stay in one place if you put a blob of it on a sloping surface. It does flow under slight pressure however, so will easily move between the gaiter and the rack as you turn the steering from lock to lock, just as oil is meant do". -- John