how does one replace the large front rubber bumper on the 1974 E type?

 

You have the right idea. Those US bumpers are the worse, I think that you have the DOT to thank for that. There was a beautiful black S III on BaT Saturday (high bid $210k but reserve not met) and it had the European front bumper replacement, and it looked great. I would be interested as to the procedure. Cost, labor, availability of parts.

 

I am still looking for help on how one replaces the large rubber bumpers with the chrome bumperettes.

 

I did this on my '73 SIII in 2022. Total cost was $289 in parts, plus the cost of an angle grinder tool (about $60 at Home Depot) and a thread tap.
I got the parts at SNG Barratt. They've gone up in price since then. Links here:
BD38803 Front Over Rider Assembly - Right hand $177.58 (on backorder)
BD38804 Front Over Rider Assembly - Left hand $177.79

Steps in the process (I may have forgotten a few things since I did the job, so feel free to chime in):

1. Remove the ugly original overriders and the trim around the front of the bonnet
2. Remove the rubber pad from the front of each of the new bumper overriders. This will give you access to the mounting bolt.
3. use the angle grinder to grind the mounting posts to allow the new overriders to fit the posts. It's a trial-and-error hand-fit process.
4. Once you've got a fit, you can use the new overriders to guide where to drill the new hole in the mounting posts. Drill and tap the hole. I've forgotten the hole and thread size. You can take the mounting bolt from the new hardware to your local hardware store to get the right size tap and drill bit.
5. now you're ready to mount the new overriders. Once you do that, you need to re-mount the rubber pads on the front of the new hardware. This is a little tricky because you need to bend the tabs to keep the rubber on, and there's not good access to do it.
6. I ended up mounting them "upside down" from the original 1972 orientation. It's not original anyway and I thought it looked better but YMMV.

The good news is the entire process is reversible, so you're not giving up originality if needed one day.

I've attached a few photos of the process I followed.


Bumper post pre-work

Bumper post after drilling

Bumper post after drilling, tapping and grinding

Bumpers completed