TOPIC:

These came on an incomplete Tamiya 1:14 truck chassis project that I'm going to go in a completely different direction on, any ideas on who made them/value so I can put them on eBay would be great

Fake exhaust is in VGC, fake fuel tank/battery holder less so but both are stainless steel. Interior of battery box is 3D printed in nasty green, ends are held on with magnets. 

Banana for scale but fake exhaust is 161mm long, Fake fuel tank / battery box is 151mm wide.

TIA  

Lesu is a good point to look.
Edit: Think I found the exhaust  1/14th Scale LESU Metal Exhaust Pipe G-6069 for 1/14 RC Tractor Truck MAN Remote Control Toy Truck Model Accessories - AliExpress 26

Also Der Getriebe Doctor in Germany has many old school 1:14 truck related parts.  The Gearbox Doctor - Verksted for RC- og funksjonell modellbygging

Found the fuel tank or at least a version of it.
Might be a older model or modified by previous owner.
Leimbach 09452 "Tank" - Verkleidung für 2-fach Steuerventil-Block | Der Getriebedoktor

TY