There's really not much to load resistors.
The key is to have the finned aluminum housing to ensure heat dissipation.
Here's some 25watt units (the max wattage of a 7443 bulb is 25watt):
Amazon.com: CUTEQUEEN TRADING 2PCS 25W 8Ohm LED Load Resistors for LED Turn Signal Lights or LED License Plate Lights or DRL (Fix Hyper Flash, Warning Cancellor) with 4pc Quick wire Clip: Automotive
Make sure you mount them to metal and away from plastic, they will put off considerable heat.
And toss those cheap splicers they send with them in the garbage.
Buy some Posi-Tap units for your wire gauge (probably 20-22).
Just not sure I would buy LEDs from Amazon.
Never sure what you will be getting.
Make sure you buy CAN-BUS LED 'bulbs'
I would recommend sites where you can deal directly with the seller:
High Performance LED Car Lighting, Light Bulbs, LED Headlights, Taillights, Turn Signals, and Brake Lights
I've bought from them in the past and they will stand behind their products. I had some flank 194 LEDs burn out prematurely (less than a year) and they sent me replacements for free.
Autolumination (I've got license plate lights from them):
Automotive Household Truck Trailer RV Lighting Led Light Bulbs
GTR (a little spendy like V-LEDs)
LED Lights - Switchback Bulbs - GTR Lighting
LEDLight.com: Online Shopping for LED Lighting Products