Well, I've now bonded the battery cover into the hull floor. Later, I'll create a plate to support the MFU and battery out of styrene- a sort of internal organiser.

Here, the rear panel needs the attention of my razor saw. That engine door, and the fishtail exhausts, will have to go, as they're for the M4A3 configuration.
After 20 mins of cursing, and careful sideways sawing, I'd levelled the plate ready for the resin Firefly doors:

I shall also need the rectangular twin air filters found on M4 Ic Fireflies. That'll mean another visit to Shapeways. They should make the rear panel look more credible.

Now for fitting some of the nicer Mato metal lights guards, lifting brackets, and the travel lock for the barrel. I also fitted real bolts through the grouser air vents.
First, having removed the HL plastic guards, it made sense to test the lights to see whether they work, or not. I have spares, as they came with the brackets, but there's not much to be gained from fitting them if the (passable) existing ones will do the job.

Yep- they work.
To line the barrel lock up, I borrowed the Comet's turret (The Firefly turret has a turret ring screwed to it currently, I couldn't be ar**d to remove.

Here it is, in place, along with the other rear accessories. At some point, I'll also need some gauze for the grouser vents (that's what they're called, according to Shadock..)
It might be my eyes, but the Mato barrel lock looks quite large, for 1/16 scale; but it's too late to worry about it now...
Still loads of fine filling and finessing to do. I have to sort out the front lights next. For that, I'll need to redo the wiring to suit HL's V6.0s standards. It never seems to end... if I
ever buy another tank- it will have to be ready to run!

I'll leave plastic surgery to the NHS.
"Get your facts first, and then you can distort them as much as you please"- Mark Twain.