Incremental Backup using TAR in sco Openserver 5.0

UNIX SCO
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Incremental Backup using TAR in sco Openserver 5.0
Dear all
I am using sco openserver 5.0. I wanted to take backup of two folder (each 600 MB size) with lot of files. I used to take backup using tar command daily using a script. But the same takes more time. Is there any way to take backup of modified files only ( like tar -N in linux). I could not find the N option in the tar command.

Thanks and regards