I have the answer in this great little part. I have included 4 spacers that allow it to be fitted in almost all Tamiya trucks with "underslung" battery boxes. The box has cutout's for batteries with centre or top lead outlets so it should accommodate almost all 2S batteries.
eBay
Model Car LED 5V Roof Engineering Lights Police Car Lamp Flash for 1/10 RC Crawler Car Traxxas Trx4 FMS 1/14 Tamiya Truck SCANIA
Aliexpress UK
The Tamiya Lunch Box Mini brings the iconic Tamiya Lunch Box to life in a fun-sized 1/24 scale. The lightweight pre-painted polycarbonate body and big, tread-patterned tyres make it a joy to drive, while its compact size allows for agile handling and tight turns.
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LESU 1/14 Tamiya truck simulation with pedal fuel tank urea tank set G-6140
Aliexpress UK
eBay
Model Car 2 In 1 Sound and Light Simulation System for 1/10 RC Crawler Car TRX4 1/14 Tamiya Truck Tipper SCANIA 770S VOLVO BENZ
Aliexpress UK
Scania Logo 5th Wheel Plate Cover – 1/14 Scale RC Truck Upgrade – 3D Printed. Add a custom finishing touch to your 1/14 scale RC truck with this Scania logo 5th wheel plate cover. Designed to sit neatly over the standard 5th wheel plate, this accessory enhances realism while giving your truck a clean, detailed appearance.
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Model Simulation Rope Tensioner Fastening Belt Strap for 1/14 Tamiya Truck 1/10 RC Crawler Car Traxxas Trx4 Axial Scx10 RC4WD
Aliexpress UK
All Tamiya cars feature realistic components which can be found on any full scale vehicle. Over the last 35 years it has built a reputation of producing high quality products which are as fun and simple to build as they are exciting and dynamic to drive.
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RC Car 2 in 1 Simulation Sound and Light Simulation System for 1/14 Tamiya Truck Tipper SCANIA 770S VOLVO 1/10 RC Crawler TRX4
Aliexpress UK
It was made by Wedico for their range of RC trucks but is now fitted with a Tamiya KingPin for their 1/14 scale trucks and I used to tow it behind my Scania truck which has since been sold so I have no need for this trailer any more.
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Scaleclub 1:14 Tractor Metal Fifth Wheel Grinding Disc Base Set Assembly Suitable For LESU Tamiya Truck Model
Aliexpress UK
1x Interior floor/back plate.
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Fineline Stone guard White Windshield Baffle For 1/14 Tamiya Truck Trailer Scania 770s 56368 Retrofit a Diy Model Toy YGP-U10
Aliexpress UK
Tamiya Volvo FH16 Globetrotter 750 unassembled and unpainted cab kit, taken from new Tamiya Volvo FH16 Globetrotter 750 8x4 Tow Truck kits.
eBay
G.T. Power Model RC Police Car Voice Sound Siren for 1/10 Crawler Drift 1/14 Tamiya Truck TRX4 SCX10 SCANIA MAN HSP HPI Kyosho
Aliexpress UK