I have a Frigidaire Gallery Series glass top stove that was cracked. I found the top assembly and glass replacement part online (part#316251921) for ~$350. However, I’m trying to see if it is possible to just replace the glass cheaper and not the entire top assembly.
Here are your pats
http://www.appliancepartspros.com/partsearch/modelsearch.aspx?model=GLEF378CQA
The stove top is Item 16 in Section 3.
Unfortunately it does not show a glass only option and if there was one it would be in this section.
Perhaps the following will be of some help to you since I could not be much help above.
http://frigidaireservicetips.com/pdfs/344_UpdateforElectricFreestandingElectricRanges_Rev.pdf