ford motors

hello, i am having problems finding the motor i want. i have a 68 mustang fastback, and i am looking for a 351 or 390. but i dont know how to tell the diffrence between them is there any specific iteams
that i can lookf for that will help me determen what motor is what size?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.