Are the tm prefixed deletion strains available and, if so, from where?
They are indeed! from the National Bioresource Project in Japan, through Shohei Mitani http://www.shigen.nig.ac.jp/c.elegans/index.jsp
The tm alleles correspond to mutants generated in Shohei Mitani’s lab. Many of them are strictly deletions, but some of the strains are deletions with small insertions.
I would suggest seeing if these mutants have been deposited in the CGC first before contacting the Mitani lab since it’s less paperwork (MTAs etc.).