as i posted in the other thread that was just linked. 
Pollokshaw Burgher split into 2 congregations (either 42 or 48 depending how you interpret the text linked in other thread). One became East Free the other Pollokshaws United Presbyterian . Juding by the number of birth records shown by using the filters on these in Scotlands People then East Free retained far more information. 
As part of finding this and looking at the list of records available in NRS i saw 2 collections containing something from these 2 churches. 
Ch3/1171- Pollokshaws Associate, Pollokshaws Burgher, Pollokshaws United Presbyterian
AND
Pollokshaws - East Free (CH3/1636) RENFREW
The entry on NRS for the first one just mentions a brief description of the church history. no details about whats in the collection.  When i filter on birth records from this "Pollokshaw Associate" then there are just 312 births 
https://catalogue.nrscotland.gov.uk/nrsonlinecatalogue/browseDetails.aspx?reference=CH3/1171&st=For the NRS entry on the EAST FREE Collection. 
https://catalogue.nrscotland.gov.uk/nrsonlinecatalogue/browseDetails.aspx?reference=CH3/1636&st=It says -
This collection has been arranged in the following way -
1. Kirk Session Minutes - no records listed
2. Board Minutes - no records listed
3. Financial Records - no records listed
4. Communion Rolls - no records listed
5. Baptismal Registers
6. Marriage Proclamation Registers - no records listed
7. Marriage Registers - no records listed
8. Commemorative Records - no records listed
9. Organisation Records - no records listed
10. Photographs - no records listed
11. Other sections
But i am not sure if "no records listed" means they have nothing like that in the collection or not..
In addition, Theres a seperate sublisting for CH3/1636/5/1. It says that access to this is closed as its not fit for production. but theres digital copies viewable. 
So, whilst ive found out more, I am none the wiser on if its worth trying to go visit these in person to see if theres any more information than whats available already via Scotlands people. Are there anything but birth records in these collections? What makes it complicated is that the one i link to first is apparently in the Glasgow City Archives - Mitchell Library. Whereas the second one is in Edinburgh. I definitely dont have time for both unfortunately. 
TBH if theres no real prospect of finding anything extra id rather spend my day of free time next week looking around Glasgow or Edinburgh instead!