What number Series 152 coil do I use?

A quick learner from Montgomery NY says:
I need to replace parts of my replacement window, and i matched my window with the following parts:

Pivot true bar 26-030
Pivot Lock shoe 15-177
Balance Drum 15-157
Drum Holder 15-185

My question is; What number coil do i use? Is it the 3LB or 4LB of the 152 series? One is stamped CL and the other is stamped B.
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Paul from SWISCO responded:
Thanks for posting! Could you please give us the weight of your window sash? This may help us figure out what you need!
A quick learner from montgomery ny says:
what? you mean take folding half of window out and put it on a scale.
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Paul from SWISCO responded:
Yes, but you would have to remove the sash fully from the window. Simply folding it down on a scale won't give us the full weight. Please let me know what you come up with!
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