I am having trouble finding the Serta version, could it be made by Sealy?

Whether it is made by Serta or Sealy, neither of those companies uses pocketed coils in their mattresses. Only Beautyrest (by Simmons) has true pocketed coils. Other companies attempt to copy the Simmons Marshall coil but cannot exactly copy it due to patents. The Simmons pocketed coil is a 10" coil power packed into an 8" sleeve so it is already under pressure the second you lie down. This gives you better support without having to sink too far into the mattress. The Simmons pocketed coil is also barrel shaped (thicker in the middle than on the ends). This prevents the coils from rubbing against one another and possibly getting stuck on one another when you get into or out of the mattress, or roll over in bed.
Sealy uses several different coil counts on their different levels of PosturePedic mattresses so you'll have to know the specific mattress to find out the exact coil count. Just best guess, it probably has around 800 wrapped (not pocketed) coils in a queen. Have a great day!