difference between SZD-48-1 and SZD 48

Any Jantar experts out there?

What the difference between an SZD-48-1 and SZD? I don't really know
that much about these aircraft. At the moment I'm trying to help
resolve an issue with play in the ailerons on a glider that is suppost
to be an SZD-48-1. One of the control rods has a lot of wear from the
rollers and needs to be replaced. The control rode from the SZD-48-1
parts catalog really doesn't match the one from the glider.

The Tech has an entry in 1978 stating the following:
convert to SZD-48-1 from SZD 48

On other thing I noticed is that this glider had side vents on the
fuse that I never noticed in the parts catalog. Did the factory make
mutant jantars??? Wondering if I need an SZD 48 catalog??

Any help would be appreciated. The serial number is w856.

Thanks