I have an ImacG5 and need to put OSX 10.5 on it to install a new printer. It presently is running PowerPC G5 (3.1)

Yes.

(65463)

Mac OS X 10.5 Leopard installation system requirements

http://support.apple.com/kb/TA24950

Leopard is no longer available at the Apple Store but may be available by calling Apple Phone Sales @ 1-800-MY-APPLE (1-800-692-7753).

If you can't obtain a retail install DVD from Apple, look on eBay or Google the installer part numbers to possibly find at an on-line store. Here's what to look for:

MB427Z/A Leopard 10.5.1 install DVD

MB576Z/A Leopard 10.5.4 install DVD

MB021Z/A Leopard 10.5.6 install DVD (single user)

MB022Z/A Leopard 10.5.6 install DVD (5-user family pack)

Installing Mac OS X 10.5 Leopard

http://support.apple.com/kb/HT1544

Mac OS X 10.5 Leopard Installation and Setup Guide

http://manuals.info.apple.com/en/leopard_install-setup.pdf

After you install the base 10.5, download & install the 10.5.8 combo update at http://support.apple.com/downloads/Mac_OS_X_10_5_8_Combo_Update

 Cheers, Tom 😉

Be careful with iMac G5's!

Many of the early models were manufactured with capacitors that eventually failed. Apple extended its warranty for these models, but that program is long over.

In general any "older" Mac (or any computer for that matter) has many parts that are likely to fail over time, so BACKUP, BACKUP, BACKUP!

Leopard OS X 10.5.x is the last OS X that will run on the iMac G5; there is no upgrade path after Leopard.