[galaxy-user] mm7 chromosome name

Hello, I have a set of coordinates for mm7 that I have been using try to extract the genomic sequences. However it doesn't recognize the chromosome name column. The are currently listed as chr1, chr2, ....chrX. This is the error I get each time I try to extract sequences:

Chromosome by name 'chr1' was not found for build 'mm7'. Skipped 1181 invalid lines, 1st is #1, "chr1 4558068 4561910 region_0 0 +"

However if I change the build to mm10 it works fine - but the coordinates are not the same between builds. Also, mm7 can't be lifted over to mm9 or mm10.

Does anyone know the proper format for chromosome name in mm7:

Thanks, Jill