LoB Hi, First of all I heartily endorse Roy's (43RR) praise of "Phillipats" PZ4 build, I am certainly not the only member of this Forum who has been impressed by the quality of his work,
For the moment I will restrict myself to just two sites that might be helpful, ----
http://www.shapeways.com
Then type in "ALL PRODUCTS TAGGED 1/16",
"Wibbly" (Warren) of this Forum Prints some great PZ4 Spares for Shapeways that adorn my PZ4s including working Front and rear Fenders, You can also get a replacement Mantlet as well as cableholders,
I warn you Shapeways is a bit like a bag of peanuts, You can't stop once you start. You can even get a 1/16 full detail Maybach 120 engine for your Tank if you don't mind parting with £130
You mentioned the rear convoy light which makes me wonder if you have thought about a "Notek front light which you will find at any dealer selling the convoy light.
As to the Radio because of the restricted space in a PZ4 I would suggest the CLARK Board it fits inside the Heng Long RX18 holder whereas the other boards are all bigger,,
The second site I would recommend is----
http://www.heng-long-panzer.de
You need to click on the German flag and up pops the Union flag with an English language translation,
Again a lot to see and is also a place to buy a CLARK board, (I got mine from here)
I will watch your build with great interest.
Shaun.