How to access array elements in Surface Vertex shaders?

Hi I'm having trouble accessing elements from an array I'm passing into a custom surface shader, here's the properties and the vertex function of the shader, I've checked and the index I get is correct, however the array doesn't seem to work, Is this incorrect syntax? Or is this not even possible? I thought I'd read that is was

     Properties {
         _Color ("Color", Color) = (1,1,1,1)
         _MainTex ("Albedo (RGB)", 2D) = "white" {}
         _Glossiness ("Smoothness", Range(0,1)) = 0.5
         _Metallic ("Metallic", Range(0,1)) = 0.0
         _EmissionColor ("Emission",Color) = (1,1,1,1)
         _Age ("Age",float) = 0.0
                             
     }
     SubShader {
         Tags { "RenderType"="Opaque" }
         LOD 200
         
         CGPROGRAM
         // Physically based Standard lighting model, and enable shadows on all light types
         #pragma surface surf Standard fullforwardshadows vertex:vert
 
         // Use shader model 3.0 target, to get nicer looking lighting
         #pragma target 3.0
 
         sampler2D _MainTex;

         half _Glossiness;
         half _Metallic;
         fixed4 _Color;
         half3 _EmissionColor;
         float _Age;
         
         float3 _Velocity[982];
         
         void vert (inout appdata_full v) {
             int index = v.texcoord1[0];
             float3 vel = _Velocity[index];
               v.vertex.xyz = vel;
               
       }//surface function code here...

Here's my code for setting the array, is this correct? (I know that the index will only go up to 982) Thanks in advance!

 for (int i=0; i<982; i++) {
             Vector3 tmp = new Vector3();
             tmp.x = m_velocities[i].r;
             tmp.y = m_velocities[i].g;
             tmp.z = m_velocities[i].b;
 
             tmpMat.SetVector("_Velocity"+i.ToString(),tmp);
         }