On your rear brake cylinders the early ones have casting numbers 5453825-4 and 5453825-5.
5453825-4 -> Part No 5453866 Rear Front
5453825-5 -> Part No 5453865 Rear Rear
The second series has casting number 5454251 on both cylinders but one cylinder has an extra tapped hole for the brake hose fitting.
Part No 5454313 Rear Front
Part No 5454251 Rear Rear
Another listing refers to 51-53 as having "vertical cylinders" and 53-59 as having "diagonal cylinder".
On 1954's, the short brake line between the cylinders has unique nuts on the flares. I was able to find a pair NOS for $$$ but it saved me a bunch of time trying to make a new pair.
Connector brake line.
'51-'53 Part No: 3697735
'53-'59 Part No: 3704424
I Googled the p/n to find the one's I bought.
