Credits Question for E38 ECM/ T42 TCM for LS3/4L80e Swap Application

[lxcoupe]

I'm doing an LS3/4L80e swap in an old C10. I know I need an E38 ECM/ T42 TCM. A good place to get this combo is a 2008-2009 Express Van or 2008-2009 Silverado. I'll be buying them used, individually.

My question relates to buying the least amount of credits and being able to fire the truck for the first time after VATS has been disabled. There are guys on eBay that will sell you a T42 TCM from an Express Van/ Silverado and program your VIN on it (aka the VIN from the HPT ECM file I'm using).

Will I need to buy credits for both the ECM and TCM if the TCM has been prevously programmed with the same VIN as the ECM tune file?

[ScarabEpic22]

T42 TCMs are free when you license the ECM in a supported license combo.

Focus on getting the same ECM and TCM platform, i.e. Express ECM and Express TCM. The ECM matters more than the TCM.

I believe it should only be 2 credits, however if you need to swap OSs you may have to use another 2.