Not heaps of manual wagons out there, I got super lucky to find mine (even so the M46 has a horrible reputation). Best option would be to grab a 740 wagon in auto and swap a T5 in. Most common swap, plenty of documentation. If you're not exclusively looking for an early front end, don't rule out the 940, 960 and v90. Otherwise you'll want a 745 or 765.
Currently there are no 745/765s listed on facebook, Gumtree or Carsales. There is one 945
(https://www.facebook.com/marketplace/item/808647357327920/?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp%3Ae8bcc6da-6ece-4ac7-8c1c-81eedaec04f0)
Otherwise
- Keep an eye out in the I Roll Volvo Australia, Volvo Sales Australia, etc Facebook Groups
- Check marketplace periodically (http://fbmpns.gmoz.biz/ to search nationwide)
- Check Gumtree
If you would like to add me on Facebook, I check 740 listings pretty religiously and would happily forward them your way.