David, you are correct about the ALS5 being designed to be an external unit, and the CLS4 being an internal unit. Please see:
https://web.archive.org/web/20020625...-html/asl5.htm
https://web.archive.org/web/20020623...-html/csl4.htm
It makes me wonder if the person who put these together put the two in series for extra roll-off?
Hopefully the GQRP will be able to supply the data. Otherwise it should not be too difficult to work out the connections.
73 John