[Big Buford]

If you're paying for a new part that should fit and doesn't, then time to return it. If you're not doing anything special with your truck, then I might suggest getting a used rad from the junkyard. You can clean it and pressure test it off the vehicle to ensure proper function. Then should be an easy fit.....

 

[Big Buford]

208 is fine as oldeerslayer said. Using water for leak testing is ok. It won't cool as efficiently as a proper mix of coolant and water. Depending on operating conditions, the water might be good enough to operate without overheating.

After testing completes, it can be a bit challenging to get to the correct mix of water and coolant though. When you drain the water, there will always be some remaining in the system. Make sure you account for the water that could not be drained when you're adding coolant/water mix for regular use.....